Dissolvable hydrogel compositions for wound management and methods of use

ABSTRACT

The inventions provided herein relate to dissolvable hydrogel compositions and methods of uses, e.g., but not limited to, in wound management. Accordingly, methods for wound management involving the dissolvable hydrogel compositions are also provided herein. In some embodiments, the dissolvable hydrogel composition comprises an adhesive thioester hydrogel, which can facilitate adherence of the dissolvable hydrogen composition to a surface (e.g., a wound) and can be controllably dissolved later upon addition of a thiolate compound to release the dissolvable hydrogel composition from the surface (e.g., the wound).

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims benefit under 35 U.S.C. §119(e) of the U.S.Provisional Application No. 61/841,746 filed Jul. 1, 2013, the contentof which is incorporated herein by reference in its entirety.

GOVERNMENT SUPPORT

This invention was made with Government Support under Contract No.EB013721 awarded by the National Institutes of Health. The Governmenthas certain rights in the invention.

TECHNICAL FIELD

The inventions described herein generally relate to dissolvable hydrogelcompositions, kits comprising the same and methods of uses. In someembodiments, the dissolvable hydrogel compositions and kits describedherein are formulated for wound management.

BACKGROUND

Skin is an organ that can be damaged by disease or injury. Skin plays avital role of protecting the body from fluid loss and disease. Skingrafts have been prepared previously from animal skin or the patient'sskin, more recently “artificial skin” formed by culturing epidermalcells. In U.S. Pat. No. 4,485,097 Bell discusses a skin-equivalentmaterial composed of a hydrated collagen lattice with platelets andfibroblasts and cells such as keratinocytes. U.S. Pat. No. 4,060,081, toYannas et al. discuss a multilayer membrane useful as synthetic skinformed from an insoluble non-immunogenic and a non-toxic material suchas a synthetic polymer for controlling the moisture flux of the overallmembrane. In U.S. Pat. No. 4,458,678, Yannas et al. discuss a processfor making a skin-equivalent material wherein a fibrous lattice formedfrom collagen cross-linked with glycosaminoglycan is seeded withepidermal cells. However, one of the disadvantages to these artificialskins is that the matrix is formed from a “permanent” synthetic polymer.Thus, these artificial skins are not dissolvable. Additional limitationsof these materials are also discussed in Yannas and Burke, J. Biomed.Mater. Res., 14, 65-81 (1980).

Classical suture technique is another method for treatment of a woundclosure. However, depending on the type and/or origin of a wound as wellas the location of a patient, use of tissue adhesives (e.g., glues,sealants, patches, films and the like) can be a more attractivealternative to use of sutures. In addition to an easy and fastapplication on a wound, other criteria for an adhesive include, but arenot limited to an ability to bind to a tissue (necrosed or not,sometimes wet) with an adequate adhesion force, non-toxic material,biodegradable or resorbable material, sterilizable material, materialselectively permeable to gases but impermeable to bacteria and able tocontrol evaporative water loss, material mechanically strong enough toprotect the wound and to enhance the healing process or at least notprevent it. Adhesive hemostats, based on fibrin, have been previouslyused and are usually constituted of fibrinogen, thrombin and factorXIII, as well as fibrinogen/photosensitizers systems. However,autologous products (which are time-consuming in emergency) ortreatments of allogenic products before clinical use are needed to avoidany contamination to a patient.

Synthetic materials, e.g., polymers and hydrogels, have been developedfor wound closure. For example, alkyl-cyanoacrylates (“super glues”)have been previously discussed for the repair of cornea perforations.However, monomers of these “super glues,” in particular those with shortalkyl chains, can be toxic and polymerize too quickly, leading todifficulty in treating a wound. Once polymerized, the surface of theglue is rough and hard. This can cause discomfort to the patient and,for example, in case of cornea perforation treatment, a contact lensneeds to be worn. Other materials have been commercialized such as“Biobrane II” (composite of polydimethylsiloxane on nylon fabric) and“Opsite” (polyurethane layer with vinyl ether coating on one side). Anew polymeric hemostat (poly-N-acetyl glucosamine) has been assessed forbiomedical applications such as treatment of gastric varies in order toreplace cyanoacrylate (Kulling et al., Endoscopy, 30(3): S41-42 (1998)).Adhesives based on modified gelatin are also found to treat skin wounds.Photopolymerizable poly(ethylene glycol) substituted with lactate andacrylate groups are previously discussed for sealing air leaks in lungsurgery.

Sealants and adhesives can help patients recover from surgery or trauma.There are medical sealant/adhesive products, CoSeal™, DuraSeal™, andAdherus®, currently existing in the market that are based on hydrogelformulations. These products comprise multiple components housed inseparate containers. CoSeal™ Surgical Sealant (CoSeal™) is composed oftwo synthetic polyethylene glycols (PEGs), a dilute hydrogen chloridesolution and a sodium phosphate/sodium carbonate solution. The DuraSeal™Dural Sealant System consists of components for preparation of asynthetic, absorbable sealant and an applicator for delivery of thesealant to the target site the sealant is composed of two solutions, apolyethylene glycol (PEG) ester solution and a trilysine amine solution.Adherus® is composed of two solutions of polyethylene glycol (PEG) esterNHS derivative and polyalkyleneimine.

Fibrin glues are also sold in packaging and applicator systems that aresimilar to those used for CoSeal™ and DuraSeal™. One example is Baxter'sTisseel. Tisseel VH (Fibrin Sealant) consists of a two-component fibrinbiomatrix that offers highly concentrated human fibrinogen to sealtissue and stop diffuse bleeding. However, all of the existing wounddressing, sealants or glues cannot be dissolved after application to thetissue site. That is, they have to be removed by mechanical debridementand/or surgical incision, if needed.

Hydrogels are one class of biomaterials currently used in medical andclinical applications, including sealing of wounds. See, e.g., Ruan, L.et al, PNAS 2009, 106, 5105-5110; Aboushwareb, T. et al. J. Biomed.Mater. Res. Part B: Appl. Biomater. 2009, 90B, 45-54; Hattori, H. etal., Annals of Biomedical Engineering, 2010, 38, 3724-3732; and Luo, Z.et al. Biomaterials, 2011, 32, 2013-2020. Hydrogels can be used ascoatings (e.g. biosensors, catheters, and sutures), as “homogeneous”materials (e.g. contact lenses, burn dressings, and dentures), and asdevices (e.g. artificial organs and drug delivery systems) (Peppas, N.A. Hydrogel in Medicine and Pharmacy, Vol I and II 1987. Wichterle, O.;Lim, D. Nature 1960, 185, 117-118. Ottenbrite, R. M.; Huang, S. J.;Park, K. Hydrogels and Biodegradable polymers for Bioapplications 1994;Vol. 627, pp 268).

Synthetic hydrogel based hemostats/sealants can offer a number ofadvantages because the chemical composition of the hydrogels can betuned for various properties, e.g., but not limited to, water content,sensitivity to environmental conditions (e.g., but not limited to, pH,temperature, solvent, stress), softness, tissue adhesion, rubberyconsistency, mechanical, degradation, and swelling properties. However,we are not aware of a hydrogel reported, e.g., for emergency care, wherea hydrogel is applied to a wound and can be subsequently removed toallow for definitive surgical care at the hospital.

A desirable or useful hydrogel or sealant system, e.g., for traumascenarios sustained in military injuries or in rural or wildernesssettings, should: (1) provide consistent hemostasis for several hours;(2) adhere to the tissue; (3) be easily applied; (4) enable controlleddissolution of the sealant in the surgical theatre setting to allow forgradual wound re-exposure during definitive surgical care. Alam, H. B.et al. Military Medicine 2005, 170, 63-69. However, we are not aware ofa dissolution capability present in any available wound hemostaticsystem as discussed above. Indeed, removal of a clotting agent ordressing from a wound is currently performed via mechanical debridementand/or surgical excision, which could potentially cause additionaldamage to tissue at and/or surrounding the wound. Accordingly, there isa need for an improved wound dressing or sealant composition, e.g., foruse in wound management.

SUMMARY

Existing materials for use in wound dressings, sealants or clottingagents are generally not reversible or dissolvable. Thus, once adressing material is adhered on a wound and/or tissue surrounding thewound, mechanical debridement or surgical incision is usually requiredif the dressing material is desired to be removed or replaced later. Yetthe physical removal process can cause additional tissue damage ortrauma or pain. Accordingly, there is a need for an improved materialfor wound management such that it can be easily or controllably removedfrom a wound in a minimally invasive manner if needed. Embodiments ofvarious aspects described herein stem in part from development ofthioester hydrogels that are not only mechanically strong, e.g., for useas a sealant, dessing, bandage, glue, or scaffold, but can also adhereto a surface and be controllably removed or dissolved on-demand later bycontacting the hydrogels with a thiolate compound/composition. Suchdissolution capability of thioester hydrogels allows for gradualre-exposure of a surface, e.g., a wound surface for further examinationand/or treatment.

In a particular embodiment, a thioester hydrogel derived frommulti-thiol-containing linear, branched, and/or dendritic macromolecules(e.g., but not limited to multi-thiol-containing peptide dendrimers,and/or dendrons) and activated ester-containing linear, branched, and/ordendritic macromolecules (e.g., but not limited to, activatedester-containing poly(ethylene glycol)) was developed and assessed forits mechanical properties, adhesive strength, and controlled dissolutionin the presence of a thiolate composition (e.g., a thiolate solution)when it was applied on a skin tissue or as a sealant to seal a bloodvessel puncture or as a bandage to treat a burn wound.

In some embodiments, a thioester hydrogel can be derived frommulti-thioester-containing linear, branched, and/or dendriticmacromolecules (e.g., but not limited to multi-thioester-containingpeptide dendrimers, and/or dendrons), and activated ester-containinglinear, branched, and/or dendritic macromolecules (e.g., but not limitedto activated ester-containing poly(ethylene glycol)). In someembodiments, a thioester hydrogel can be derived frommulti-amine-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine-containing peptide dendrimers,and/or dendrons) and activated ester-thioester-containing linear,branched and/or dendritic macromolecules (e.g., but not limited to,activated ester-thioester-containing polyethylene glycol)). In someembodiments, a thioester hydrogel can be derived from multi-amine- andthioester-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine- and thioester-containing peptidedendrimers, and/or dendrons) and activated ester containing linear,branched and/or dendritic macromolecules (e.g., but not limited to,activated ester-containing poly(ethylene glycol)). In some embodiments,a thioester hydrogel can be derived from multi-amine- andthioester-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine- and thioester-containing peptidedendrimers, and/or dendrons) and activated ester-thioester-containinglinear, branched and/or dendritic macromolecules (e.g., but not limitedto, activated ester-thioester-containing poly(ethylene glycol)). In someembodiments, a thioester hydrogel can be derived frommulti-thiol-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-thiol-containing peptide dendrimers,and/or dendrons) and maleimide-thioester-containing linear, branchedand/or dendritic macromolecules (e.g., but not limited to,maleimide-thioester-containing poly(ethylene glycol)).

Accordingly, embodiments of various aspects described herein relate todissolvable hydrogel compositions, kits, and methods of uses. Thedissolvable hydrogel compositions each comprises a thioester hydrogel(e.g., as a layer), which can be dissolved and/or washed away byaddition of a composition comprising at least one nucleophile. In oneembodiment, at least one nucleophile comprises a thiol moiety. Thedissolvable hydrogel compositions can be optionally loaded with one ormore biologically and/or pharmacologically active agent and/orchemically modified to contain or couple to active agent(s).

The dissolvable hydrogel compositions, kits and/or methods describedherein can be used in any application where a surface or void (e.g., aphysical or environmental surface/void or a biological surface/void)needs to be covered, filled, and/or sealed. In some embodiments, thedissolvable hydrogel compositions, kits, and/or methods described hereincan be used in any application where a surface or void requirestemporary and/or immediate treatment, covering and/or structuralsupport, which can be removed later to expose the surface or void foradditional care and/or management (e.g., but not limited to,examination, drug treatment, and/or surgical treatment). In theseembodiments, a new composition, but not necessarily a new dissolvablehydrogel composition described herein, can be applied on the exposedsurface, if necessary.

Accordingly, in some embodiments of various aspects described herein,the dissolvable hydrogel compositions, kits and methods of usesdescribed herein can be used for wound management, e.g., but not limitedto, sealing, treating, and/or repairing wounds, treatment of burns orother traumatized or degenerative tissue, or repair or replacement oftissues or organs. In some embodiments of various aspects describedherein, the hydrogel compositions, kits and methods of uses describedherein can be used for wound management with vacuum assisted closure.

In some aspects, methods for wound management are provided herein. Inone aspect, the method comprises (a) contacting a wound in a subjectwith a hydrogel composition comprising a dissolvable hydrogel layer,wherein the dissolvable hydrogel layer comprises linear, branched,and/or dendritic crosslinkable polymers held together by thioesterlinkages formed between the first crosslinkable polymer and the secondcrosslinkable polymer; and (b) allowing the dissolvable hydrogel layerto adhere to tissue surrounding the wound. In some embodiments, themethod further comprises dissolving the dissolvable hydrogel layer byadding a nucleophile, thereby releasing the hydrogel layer from thewound. In one embodiment, the nucleophile can comprise a thiolatecompound or molecule. In some embodiments, the first crosslinkablepolymers and the second crosslinkable polymers do not necessarilypossess thioester linkage or functional group in their molecularstructures. In these embodiments, thioester linkages present within adissolvable hydrogel can result or be formed from covalent interactionbetween the first crosslinkable polymers and the second crosslinkablepolymers. For example, the thioester linkages present within adissolvable hydrogel can result from reacting a first crosslinkablepolymer comprising at least two thiols with a second crosslinkablepolymer comprising crosslinking moieties (e.g., but not limited toN-succinimidyl moiety and/or activated ester groups), wherein neither ofthe crosslinkable polymers has any thioester bonds in their molecularstructure.

In another aspect, the method comprises (a) contacting a wound in asubject with a hydrogel composition comprising a dissolvable hydrogellayer, wherein the dissolvable hydrogel layer comprises first linear,branched, and/or dendritic crosslinkable polymers and second linear,branched, and/or dendritic crosslinkable polymers covalently heldtogether, wherein the first crosslinkable polymers and/or the secondcrosslinkable polymers comprise at least one thioester linkage orfunctional group in their molecular structures; and (b) allowing thedissolvable hydrogel layer to adhere to tissue surrounding the wound. Insome embodiments, the method further comprises dissolving thedissolvable hydrogel layer by adding a nucleophile, thereby releasingthe hydrogel layer from the wound. In one embodiment, the nucleophilecan comprise a thiolate compound or molecule. In these embodiments, atleast some of the thioester linkages present within a dissolvablehydrogel network can be contributed from one or both of the firstcrosslinkable polymers and the second crosslinkable polymers thatcomprise a thioester linkage or functional group in their molecularstructure. For example, the thioesters can be present within thecrosslinkable macromolecules or polymers such that a new covalent bondis formed (e.g., amide) which results in a hydrogel containing thioesterlinkages. In some embodiments, the first crosslinkable polymers and/orthe second crosslinkable polymers can be covalently linked together viaany art-recognized chemical reactions, including, e.g., but not limitedto an amine-ester reaction.

In some embodiments of various aspects described herein where vacuumassisted closure is applied, the method can further comprise removingthe dissolved hydrogel from the wound with vacuum.

Without wishing to be bound by theory, a thiol-thioester exchangereaction between thioester linkages present in the dissolvable hydrogellayer and thiols of a thiolate compound or molecule leads to dissolutionof the dissolvable hydrogel layer. In some embodiments, thethioester-thiol exchange can also result in formation of an amidelinkage, thereby preventing re-formation of the dissolvable hydrogel.

In some embodiments of this aspect and other aspects described herein,the hydrogel composition can be present as a thin sheet or layer. Insome embodiments of this aspect and other aspects described herein, thehydrogel composition can be present as a thin sheet or layer supportedby a sheet support member to provide mechanical strength. In alternativeembodiments of this aspect and other aspects described herein, thehydrogel composition can be a multi-layer composite comprising at leastone layer of the dissolvable hydrogel layer described herein and atleast one additional layer. The additional layer can be a drug-releasinglayer, another material layer (e.g., another polymer layer), and/or asheet support member.

In some embodiments of this aspect and other aspects described herein,the hydrogel composition can further comprise at least one active agent.The active agent can be incorporated into the dissolvable hydrogel layerand/or additional layer(s), if any. In some embodiments, the activeagent can be a bioactive agent. Non-limiting examples of bioactiveagents include pharmaceutical agents, drugs, cells, gases and gaseousprecursors, synthetic organic molecules, proteins, enzymes, growthfactors, vitamins, steroids, polyanions, nucleosides, nucleotides,polynucleotides, polymer nanoparticles, metal nanoparticles, diagnosticagents, genetic materials, and any combinations thereof.

The hydrogel compositions of various aspects described herein can beadapted to form any wound management devices or articles, e.g., but notlimited to, a dressing, bandage, glue, sealant, coating, and/orcovering. In some embodiments, the hydrogel compositions of variousaspects described herein can be adapted for use with vacuum assistedclosure. Accordingly, one aspect described herein relates to adissolvable hydrogel composition or a wound management device comprisingan adhesive hydrogel layer, wherein the adhesive hydrogel layercomprises a first water-soluble linear, branched, and/or dendriticcrosslinkable polymer and a second water soluble linear, branched,and/or dendritic crosslinkable polymer held together by thioesterlinkages between the first crosslinkable polymer and the secondcrosslinkable polymer.

The adhesiveness and reversibility of the dissolvable hydrogel describedherein provide a novel means of wound management. The dissolvablehydrogel layer or the dissolvable hydrogel composition or the woundmanagement device can be dissolved partially or completely, wheneverappropriate, after the dissolvable hydrogel layer is adhered to tissuesurrounding a wound. In accordance with embodiments of various aspectsdescribed herein, the dissolvable hydrogel layer can be dissolved,partially or completely, by addition of a thiolate compound or molecule.Examples of thiolate compounds/molecules include, without limitations,linear, branched and/or dendritic multi-thiol macromolecules,poly(ethylene glycol) thiol, thiol-containing glycerol, thiol-containingglycerol polymers, thiol-containing peptides, cysteine, cystine, alkylester of cysteine, alkyl ester of cystine, MeSCH₂SH,(R)/(S)-3-methyl-3-sulfanylhexan-1-ol, Ethanethiol, 1-Propanethiol,2-Propanethiol, Butanethiol, tert-Butyl mercaptan, Pentanethiols,Thiophenol, Dimercaptosuccinic acid, Thioacetic acid,5-mercapto-4H-[1,2,4]triazol-3-ol, 2-mercaptoacetamide,2-Mercaptoethanol, 1,2-Ethanedithiol, Ammonium thioglycolate,Cysteamine, Methyl thioglycolate, Thiolactic acid,1-Mercapto-2-propanol, 2-methoxyethanethiol, 3-Mercapto-1-propanol,2,3-Dimercapto-1-propanol, 1-Thioglycerol, Mercaptosuccinic acid,4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol, N-Carbamoyl-L-cysteine,2-Methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid,N-Acetylcysteamine, 3-Methyl-1-butanethiol, 1,5-Pentanedithiol,4-Chlorothiophenol, 4-Aminothiophenol, Benzyl mercaptan,2-furanmethanethiol, 3-mercaptohexanol, furfuryl thiol, derivativesthereof, a disulfide complex of one or more of the aforementionedcompounds, and any combinations thereof.

The thiolate compound/molecules can be formulated in any form to suitthe application format, e.g., but not limited to spraying and/orinjection. In some embodiments, the thiolate compound/molecules can beformulated in a form of a solution, a spray, a powder, or anycombinations thereof.

Additional objects, advantages, and features will become apparent fromthe following description and the claims that follow, considered inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are schematic representations, respectively, showingchemistry of native chemical ligation (NCL) (FIG. 1A). and across-linked PEG-LysSH hydrogel (in accordance with one embodimentdescribed herein) formed between Dendron 1 andN-hydroxysuccinimide-containing PEG molecule 3 (e.g., SVA-PEG-SVA) andits reversibility based on NCL (FIG. 1B).

FIG. 2 shows an exemplary scheme of a synthetic route to formPEG-peptide dendrons 1 and 2. The alphabets in the figure indicateprocess condition as described follows: (a) MPEG2000-NH₂, DIPEA, HOBT,EDCI, DMF, room temperature, 16 hrs, 90%; (b) Pd/C, H₂ (1 atm), MeOH,room temperature, 16 hrs, 90%; (c) PFP-3(tritylthio)propionic acid,HOBT, DMF, room temperature, 24 hrs, 76%; (d) Et₃SiH, TFA, DCM, roomtemperature, 3 hrs, 95%. Cbz=benzyloxycarbonyl,DIPEA=diisopropylethylamine, DMF=N,N-dimethylformamide,EDCI=1-(3-dimethylaminopropyl 3-ethyl-carbodiimide,HOBT=1-hydroxybenzotriazole, PFP=pentafluorophenol, Tr=trityl,TFA=trifluoroacetic acid.

FIG. 3 is a bar graph showing the storage modulus G′ of dissolvablehydrogel compositions according to one or more embodiments describedherein before and after 48-hour swelling. The storage modulus G′ wasperformed for ˜10 wt % and ˜30 wt % PEG-LysSH and ˜30 wt % PEG-LysNH₂hydrogels at ˜50 Pa oscillatory stress, ˜1 Hz frequency, and ˜20° C.

FIG. 4 is a line graph showing the reversibility of PEG-LysSH andPEG-LysNH₂ hydrogels at ˜30 wt % upon exposure to differentconcentrations of (L)-cysteine methyl ester (CME) in a bufferedsolution, e.g., PBS, at different pHs, e.g., pH ˜7.4 and pH ˜8.5, or to˜0.3 M (L)-lysine methyl ester (LME) in PBS at pH ˜8.5, or to ˜0.3 M2-mercaptoethancsulfonate (MES) in PBS at pH ˜8.5. Storage moduli G′values were normalized to the highest G′ value for each experiment.

FIGS. 5A-5C are photographs showing adhesion strength and dissolution ofhydrogels PEG-LysSH and PEG-LysNH₂. FIGS. 5A-5B are photographs ofhydrogels PEG-LysSH (green; upper panel) and PEG-LysNH₂ (pink; lowerpanel) adhered to human tissue skin, under torsional stress. FIG. 5C isa set of photographs showing dissolution of PEG-LysSH hydrogel in ˜0.3 MCME solution in PBS at pH ˜8.5, at different time intervals (0, ˜10, ˜20and ˜30 min). PEG-LysNH₂ used as control, swelled and did not dissolve.The PEG-LysSH and PEG-LysNH₂ hydrogel sealants were dyed with green foodcoloring or nile red dye, respectively.

FIGS. 6A-6F are photographs showing an example use of one embodiment ofa dissolvable hydrogel as a tissue sealant. FIG. 6A is a photograph of abeef jugular vein. FIG. 6B shows the vein linked to a syringe pump andfilled with a buffered solution, e.g., PBS at pH ˜7.4; FIG. 6C showsgeneration of a ˜2.5 mm puncture on the vein surface. FIG. 6D showsPEG-LysSH hydrogel (e.g., ˜30 wt %) applied on the puncture. Thehydrogel was dyed in green. FIG. 6E shows PEG-LysSH hydrogel (e.g., ˜30wt %) applied on a deep second-degree burn wound model. FIG. 6F is a setof photographs showing the dissolution of PEG-LysSH hydrogel uponexposure to cysteine methyl ester solution. The left panel showsapplying a cysteine methyl ester solution on the hydrogel surface. Theright panel shows complete dissolution of the hydrogel after applicationof the cysteine methyl ester solution.

FIG. 7 is a data graph showing the stability of PEG-LysSH hydrogel(e.g., ˜30 wt %) subjected to different conditions, as indicated bynormalized storage moduli G′ values. For example, reducing theequivalent number of thiols present in a thiolate solution (e.g., with apH ˜8.5) to four based on the number of thioester linkages resulted inalmost no change in mechanical properties after at least about 60minutes with the thiol-thioester exchange reaction occurring slowly. Inaddition, the PEG-LysSH hydrogel substantially maintained its mechanicalproperty after exposure to pH 0 for at least about 60 minutes. However,the mechanical property of the PEG-LysSH hydrogel decreased over time asit was exposed to pH ˜14, indicating a gradual dissolution of thehydrogel.

FIGS. 8A-8C show another embodiment of a thioester hydrogel (usingcitric acid and NHS-PEG-NHS) and its rheological properties. FIG. 8A isa schematic representation showing a chemical reaction of citric acidand cysteamine to form S,S,S-tris(2-aminoethyl)2-hydroxypropane-1,2,3-tris(carboxylothioate) hydrochloride salt(product A), which is then reacted with NHS-PEG-NHS (MW ˜2400 Da) toform a thioester hydrogel in accordance with one embodiment describedherein, as shown in step 1 of FIG. 8B. By addition of a cysteinesolution to the thioester hydrogel, the thioester hydrogel dissolved(step 2 of FIG. 8B). FIG. 8C is a bar graph showing storage modulus G′and loss modulus G″ of the thioester gel and its precursors.

FIGS. 9A-9E show another embodiment of a thioester hydrogel (usingdendron 1 described in FIG. 2 and MAL-thio-PEG-thio-MAL 9 containingthioester linkages within its structure) and its rheological properties.FIG. 9A is a schematic representation showing the reaction of theprecursors to form the hydrogel. FIG. 9B details the synthetic route ofthe second-water soluble crosslinkable macromolecule,MAL-thio-PEG-thio-MAL 9. FIG. 9C is a bar graph showing storage modulusG′ and loss modulus G″ of the thioester hydrogel. FIG. 9D shows theefficacy of the hemostatic thioester hydrogel in an in vivo model ofvenous hemorrhage (where the hydrogel was applied on a hepatic incisionof an in vivo rat model) (left panel), followed by its dissolution usingmethyl ester cysteine solution (right panel). FIG. 9E shows the efficacyof the hemostatic thioester hydrogel in an in vivo model of arterialhemorrhage (where the hydrogel was applied on an aortic incision of anin vivo rat model) (left panel), followed by its dissolution usingmethyl ester cysteine solution (right panel).

FIGS. 10A-10B show another embodiment of a thioester hydrogel (usingdendron 2 described in FIG. 2 and NHS-thio-PEG-thio-NHS 10 containingthioester linkages within its structure). FIG. 10A is a schematicrepresentation showing the reaction of the precursors to form thehydrogel. FIG. 10B details the synthetic route of the second-watersoluble crosslinkable macromolecule, NHS-thio-PEG-thio-NHS 10.

DETAILED DESCRIPTION OF THE INVENTION

In military fields or rural areas, injuries or wounds may sometimes notbe able to receive immediate medical treatment. Thus, temporary coveringand/or treatment of a wound or an injury can help minimize its exposureto pathogen infection (e.g., bacterial infection) and/or additionaltissue damage before it is attended for an appropriate medicaltreatment. However, existing materials for use in wound dressings,sealants or clotting agents are generally not reversible or dissolvableor easily detached from tissue after adhering thereto, thus currentlyrequiring mechanical debridement or surgical incision for removal of thedressings, sealants, or clotting agents to re-expose a tissue surface,e.g., a wound, for example, in order to permit further examinationand/or treatment as needed. Further, the removal process can causeadditional tissue damage or trauma. Accordingly, there is a need for animproved material for wound management such that, after the materialadheres to a wound or tissue, it can be easily or controllably removedtherefrom in a minimally-invasive manner, whenever necessary.

Embodiments of various aspects described herein stem in part fromdevelopment of thioester hydrogels that are not only mechanicallystrong, e.g., for use as a sealant or dressing, but can also adhere to asurface and be controllably removed or dissolved on-demand later bycontacting the hydrogels with a thiolate composition, to allow forgradual re-exposure of a surface, e.g., for further examination and/ortreatment. In one embodiment, a thioester hydrogel derived frommulti-thiol-containing linear, branched, and/or dendritic macromolecules(e.g., but not limited to multi-thiol-containing peptide dendrimers,and/or dendrons) and activated ester-containing linear, branched and/ordendritic macromolecules (e.g., but not limited to activatedester-containing poly(ethylene glycol)) was developed and assessed forits mechanical properties, adhesive strength, and controlled dissolutionin the presence of a thiolate composition (e.g., a thiolate solution)when it was applied on a skin tissue or as a sealant to seal a bloodvessel puncture or as a bandage to treat a burn wound. In anotherembodiment, a thioester hydrogel derived from multi-thiol-containinglinear, branched and/or dendritic macromolecules (e.g, but not limitedto multi-thiol-containing peptide dendrimers, and/or dendrons) andmaleimide-thioester-containing linear, branched and/or dendriticmacromolecules (e.g, but not limited to maleimide-containingpoly(ethylene glycol)) was also developed and assessed for itsmechanical properties, adhesive strength and controlled dissolution inthe presence of a thiolate composition (e.g., a thiolate solution) whenit was applied as a hemostatic dressing in an aortic and/or hepaticinjury model. In other embodiments, thioester hydrogels derived fromlinear, branched and/or dendritic crosslinkable polymers comprising thethioester linkages within their structures were developed and assessedfor their mechanical properties, adhesive strength and controlleddissolution in the presence of a thiolate composition (e.g. a thiolatesolution). For example, a thioester hydrogel can be derived frommulti-amine-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine-containing peptide dendrimers,and/or dendrons) and activated ester-thioester-containing linear,branched and/or dendritic macromolecules (e.g., but not limited to,activated ester-thioester-containing poly(ethylene glycol)). In someembodiments, a thioester hydrogel can be derived from multi-amine- andthioester-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine- and thioester containing peptidedendrimers, and/or dendrons) and activated ester-containing linear,branched and/or dendritic macromolecules (e.g., but not limited to,activated ester-containing poly(ethylene glycol)). In some embodiments,a thioester hydrogel can be derived from multi-amine- andthioester-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi amine-containing peptide dendrimers,and/or dendrons) and activated ester-thioester-containing linear,branched and/or dendritic macromolecules (e.g., but not limited to,activated ester-thioester-containing poly(ethylene glycol)).

Accordingly, embodiments of various aspects described herein relate todissolvable hydrogel compositions, kits, and methods of uses. Thedissolvable hydrogel compositions each comprise a thioester hydrogel(e.g., as a layer), which can be dissolved and/or washed away byaddition of a composition comprising at least one nucleophile. In oneembodiment, at least one nucleophile comprises a thiol moiety. Thedissolvable hydrogel compositions can be optionally loaded with one ormore biologically and/or pharmacologically active agent and/orchemically modified to contain or couple to the active agent(s).

The dissolvable hydrogel compositions, kits and/or methods describedherein can be used in any application where a surface or void (e.g., aphysical or environmental surface/void or a biological surface/void)needs to covered, filled, and/or sealed. In some embodiments, thedissolvable hydrogel compositions, kits, and/or methods described hereincan be used in any application where a surface or void requirestemporary and/or immediate treatment, covering and/or structuralsupport, which can be removed later to expose the surface or void foradditional care and/or management (e.g., but not limited to,examination, drug treatment, and/or surgical treatment). In theseembodiments, a new composition, but not necessarily a new dissolvablehydrogel composition described herein, can be applied on the exposedsurface, if necessary.

Accordingly, in some embodiments, the dissolvable hydrogel compositions,kits and methods of uses described herein can be used for clinicaltreatments, e.g., but not limited to, sealing, treating, and/orrepairing wounds, treatment of burns or other traumatized ordegenerative tissue, or repair or replacement of tissues or organs. Insome embodiments, the dissolvable hydrogel compositions, kits and/ormethods described herein can be used at a void, wound or injury site,e.g., but not limited to, opthalmological, orthopedic, cardiovascular,pulmonary, skin, burn, or urinary wounds and/or injuries, includingthose created during surgery as well as drug delivery and tumor removal.In some embodiments, the dissolvable hydrogel compositions, kits and/ormethods described herein can be used as a sealant, glue, dressing,and/or coating for surgical procedures where the site of the wound isnot easily accessible and/or when sutureless surgery is desirable.

While the dissolvable hydrogel compositions described herein can existin any form or part of a wound management device, in some embodiments,the dissolvable hydrogel compositions can be formulated for uses asbandages, sealants, dressing, glues, coatings, coverings, and/orscaffolds, which, if needed, can be subsequently dissolved by adding anaqueous solution of a thiol or other nucleophile revealing theoriginally-covered site. The dissolvable hydrogel compositions can beapplied to a target tissue site in any formulation, e.g., but notlimited to, a spray, liquid, foam, and/or preformed structure.

In some embodiments, the dissolvable hydrogel compositions, kits, and/ormethods described herein can be used to form a three-dimensionalscaffold, gel, matrix or template (e.g., of any shapes and/or sizes) forcell growth.

Dissolvable Hydrogels or Dissolvable Hydrogel Layers Described Herein

In one aspect, provided herein relates to compositions comprising adissolvable thioester hydrogel. As used herein, the term “hydrogel”generally refers to a hydrophilic gel regardless of the state ofhydration, and therefore includes, for example, hydrogels that are in adehydrated or anhydrous state or in a state of partial hydration.Hydrogels are generally polymers characterized by their hydrophilicity(e.g., capacity to absorb large amounts of fluid such as water or woundexudate) and insolubility in water. Thus, they are capable of swellingin water while generally preserving their shape. Stated another way, insome embodiments, a hydrogel is a polymeric material, which exhibits theability to swell in water and to retain a fraction of water within thestructure without dissolving.

Without wishing to be limited, the hydrophilicity of hydrogels isgenerally due to groups such as hydroxyl, carboxyl, carboxamide, amines,sulphonate and esters, among others. On contact with water, the hydrogelassumes a swollen hydrated state that results from a balance between thedispersing forces acting on hydrated chains and cohesive forces that donot prevent the penetration of water into the polymer network. Thecohesive forces are most often the result of crosslinking, but mayresult from electrostatic, hydrophobic or dipole-dipole interactions.

Additional information about hydrogels are described in Hydrogels,Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition, vol. 7,pp. 783-807, John Wiley and Sons, New York, the contents of which areincorporated herein by reference.

As used herein, the term “thioester hydrogel” refers to a hydrogelcomprising thioester linkages/bonds throughout the hydrogel. A thioesterhydrogel can be a hydrogel comprising crosslinkable macromolecules orpolymers held together by thioester linkages connecting between thecrosslinkable macromolecules or polymers, or a hydrogel possessingthioester linkages which are not formed from a crosslinking reactionbetween the crosslinkable macromolecules or polymers, but are conferredby the thioester groups inherently present in at least some of thecrosslinkable macromolecules or polymers.

A thioester hydrogel is a polymeric network comprising at least abouttwo or more thioester linkages, including, e.g., at least about two, atleast about five, at least about 10, at least about 20, at least about30, at least about 40, at least about 50, at least about 60, at leastabout 70, at least about 80, at least about 90, at least about 100, atleast about 500, at least about 1000 or more thioester linkages. Thenumber of the thioester linkages in a thioester hydrogel can vary withthe number of reactive functional groups present in the crosslinkablemacromolecules or polymers, or the number of thioester present in themacromolecules or polymers to be crosslinked.

In some embodiments, the thioester linkages within a thioester hydrogelcan be contributed from or conferred by at least some of thecrosslinkable macromolecules or polymers comprising the thioesterlinkages. For example, a thioester hydrogel can be derived frommulti-amine-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine-containing peptide dendrimers,and/or dendrons) and activated ester-thioester-containing linear,branched and/or dendritic macromolecules (e.g., but not limited toactivated ester-thioester-containing poly(ethylene glycol)).Alternatively, a thioester hydrogel can be derived from multi-amine- andthioester-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine- and thioester-containing peptidedendrimers, and/or dendrons) and activated ester containing linear,branched and/or dendritic macromolecules (e.g., but not limited toactivated ester-containing poly(ethylene glycol)). In anotherembodiment, a thioester hydrogel can be derived from multi-amine- andthioester-containing linear, branched and/or dendritic macromolecules(e.g., but not limited to multi-amine- and thioester-containing peptidedendrimers, and/or dendrons) and activated ester-thioester-containinglinear, branched and/or dendritic macromolecules (e.g., but not limitedto, activated ester-thioester-containing poly(ethylene glycol)).

In some embodiments, thioester hydrogels are “thioester-crosslinkedhydrogels.” The term “thioester-crosslinked hydrogel” refers to ahydrogel comprising crosslinkable macromolecules or polymers heldtogether by thioester linkages connecting between the crosslinkablemacromolecules or polymers. In these embodiments, the thioester linkageswithin the thioester-crosslinked hydrogels are resulted from covalentinteraction between the crosslinkable macromolecules or polymers. Forexample, the thioester linkages within a thioester-crosslinked hydrogelcan result from reacting a first crosslinkable macromolecule or polymercomprising at least two thiols with a second crosslinkable macromoleculeor polymer comprising crosslinking moieties (e.g., but not limited toN-succinimidyl moiety and/or activated ester groups) such that acrosslinking reaction between the first and second crosslinkablemacromolecules or polymers forms thioester linkages. In someembodiments, the first and/or second crosslinkable macromolecules orpolymers do not inherently possess any thioester groups/bonds.

In accordance with embodiments of various aspects described herein, thethioester hydrogels are dissolvable. As used herein, the term“dissolvable” refers to the capability of a hydrogel to partially orcompletely transform into a flowable state. For example, in someembodiments, the dissolvable thioester hydrogels can be transformed intoa solution upon contact with a nucleophile as described herein. In someembodiments, the dissolution process is reversible, i.e., a hydrogeldissolved into a solution can reform from the solution. In otherembodiments, the dissolution process is not reversible.

In accordance with embodiments of various aspects described herein, atleast a portion of the thioester linkages within a thioester hydrogelnetwork can react with a nucleophile that is selected to causedissociation of the polymeric network and thus dissolution of at least aportion of the thioester hydrogel. The term “nucleophile” is recognizedin the art, and as used herein generally means a chemical moiety havinga reactive pair of electrons. Any molecule or ion with electronsavailable for donation to another molecule, e.g., a free pair ofelectrons or at least one pi bond, can be considered as a nucleophile.Examples of nucleophiles include, without limitations, unchargedmolecules or moieties such as water, amines, thiols, mercaptans andalcohols, and charged moieties such as alkoxides, thiolates, carbanions,and a variety of organic and inorganic anions.

In one embodiment, the nucleophile selected for use in dissolution of adissolvable thioester hydrogel described herein includes a thiol moiety.Examples of molecules comprising at least one thiol moiety include, butare not limited to linear, branched and/or dendritic multi-thiolmacromolecules, poly(ethylene glycol) thiol, thiol-containing glycerol,thiol-containing polyglycerol, thiol-containing peptides, cysteine,cystine, alkyl ester of cysteine, alkyl ester of cystine, MeSCH₂SH,(R)/(S)-3-methyl-3-sulfanylhexan-1-ol, Ethanethiol, 1-Propanethiol,2-Propanethiol, Butanethiol, tert-Butyl mercaptan, Pentanethiols,Thiophenol, Dimercaptosuccinic acid, Thioacetic acid,5-mercapto-4H-[1,2,4]triazol-3-ol, 2-mercaptoacetamide,2-Mercaptoethanol, 1,2-Ethanedithiol, Ammonium thioglycolate,Cysteamine, Methyl thioglycolate, Thiolactic acid,1-Mercapto-2-propanol, 2-methoxyethanethiol, 3-Mercapto-1-propanol,2,3-Dimercapto-1-propanol, 1-Thioglycerol, Mercaptosuccinic acid,4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol, N-Carbamoyl-L-cysteine,2-Methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid,N-Acetylcysteamine, 3-Methyl-1-butanethiol, 1,5-Pentanedithiol,4-Chlorothiophenol, 4-Aminothiophenol, Benzyl mercaptan,2-furanmethanethiol, 3-mercaptohexanol, furfuryl thiol, a disulfidecomplex of one or more of the aforementioned thiol-containing molecules,derivatives of the aforementioned thiol-containing molecules, and anycombinations thereof. Without wishing to be bound by theory, the thiolmoiety can react with thioester moieties within the hydrogel based onthioester-thiol exchange, resulting in dissolution of at least a portionof the thioester hydrogel and optionally formation of amide linkages toprevent hydrogel re-formation.

In some embodiments, thioester hydrogels can be hydrolytically stableacross a range of various pH values. In some embodiments, thioesterhydrogels can be hydrolytically stable at pH in a range of about 0 toabout 14, in a range of about 0 to about 12, in a range of about 0 toabout 9, or in a range of about 0 to about 7. Hydrolysis ofsmall-molecule thioesters has been previously reported in the context ofthe origins of life that small molecule thioesters such as CH₃C(O)SCH₃(with a molecule weight of about 90 Da or 90 g/mol) hydrolyze ˜10,000times faster at high pH (e.g., above pH ˜7) and low pH (e.g., below pH˜3) and are relatively stable at pH ˜3 to ˜7. That is, small moleculethioesters (e.g., with a molecular weight of no more than 500 Da) arehydrolytically unstable at a pH below 3 or above 7. Surprisingly, inaccordance with various embodiments described herein, a thioesterhydrogel, which generally has high water content, is hydrolyticallystable at pH from 0 to at least about 9 (FIG. 7). Without wishing to bebound by theory, this significant increase in stability of a thioesterhydrogel can be, at least in part, a result of the polymer chainbackbone stabilizing the thioester bond, since hydrolysis of a thioesterhydrogel would require the polymer chain to change conformation orrearrange in space. As the chains are generally confined to an area viaa hydrogel, a conformational change or rearrangement of polymer chainscan become less favorable.

In some embodiments, thioester hydrogels are adhesive. For example, thethioester hydrogel can adhere to a tissue, e.g., even in the presence ofwound exudate and/or blood. In these embodiments, the thioester hydrogelcan adhere to a tissue, e.g., tissue at or surrounding a wound, and besubsequently dissolved by adding a thiolate compound, e.g., for woundmanagement.

In some embodiments, a thioester hydrogel can be a hydrogel comprising anetwork of crosslinkable macromolecules or polymers covalently heldtogether by linkages comprising a thioester moiety. For example, in someembodiments, a thioester hydrogel can be derived or formed from a firstwater-soluble macromolecule or polymer comprising at least two thiolmoieties and a second water-soluble macromolecule or polymer comprisingat least two crosslinking moieties that can react with the thiolmoieties of the first water-soluble macromolecule or polymer, to form atleast two thioester crosslinks. In some embodiments, a thioesterhydrogel can be derived or formed from a first water-solublemacromolecule or polymer comprising at least two thioester moieties anda second water-soluble macromolecule or polymer comprising at least twocrosslinking moieties that can crosslink with the first water-solublemacromolecule. In some embodiments, a thioester hydrogel can be derivedor formed from a first water-soluble macromolecule or polymer comprisingat least two nucleophilic moieties that can crosslink with at least twocrosslinking moieties of a second water-soluble macromolecule or polymercomprising at least two thioester moieties. In some embodiments, athioester hydrogel can be derived or formed from a first water-solublemacromolecule or polymer comprising at least two nucleophilic moietiesthat can crosslink with at least two crosslinking moieties of a secondwater-soluble macromolecule or polymer such that the resulting hydrogelcontains thioester moieties.

As used herein, the term “crosslinkable” in the context of crosslinkablemacromolecules or polymers refers to the ability of macromolecules orpolymers to form at least one or more covalent bonds (crosslinks) withone another to form a polymeric network (hydrogel) under a certaincondition.

As used herein, the term “water-soluble” refers to the ability ofcrosslinkable macromolecules or polymers described herein (prior to acrosslinking reaction to form a hydrogel) to dissolve in a water-basedsolution under a certain condition (e.g., temperature, pH, and/orpressure). In some embodiments, the water-based solution is water, abuffered solution (e.g., phosphate buffered saline (PBS)), saline, orsalt solution of pH in the range from 4 to 10.

As used interchangeably herein, the terms “macromolecule” and “polymer”refer to a natural and/or synthetic molecule with a molecular weight ofat least about 200 Da, at least about 500 Da, at least about 1 kDa ormore, e.g., at least about 2 kDa, at least about 3 kDa, at least about 4kDa, at least about 5 kDa, at least about 10 kDa, at least about 20 kDa,at least about 30 kDa, at least about 40 kDa, at least about 50 kDa ormore. In some embodiments, the macromolecule (or polymer) can compriserepeating structural units.

The first water-soluble macromolecule and/or the second water-solublemacromolecule can independently have a backbone in any structure, e.g.,but not limited to, linear, branched, comb-like, dendritic-likeincluding, e.g., dendrimers, dendrons and hyperbranched polymers, or anycombinations thereof.

In some embodiments, the first and the second water-solublemacromolecules can both have substantially the same or similar type ofstructure. For example, both the first and the second water-solublemacromolecules can have substantially linear structures, or both canhave substantially dendritic-like structures, or both can havestructures comprising a combination of linear and dendritic-likestructures. In some embodiments, the first and the second water-solublemacromolecules can have different type of structures, e.g., one can havea linear structure, while another can have a dendritic-like structure.In some embodiments, the first water-soluble macromolecule or the secondwater-soluble macromolecule can comprise a substantially linearstructure. In some embodiments, the first water-soluble macromolecule orthe second water-soluble macromolecule can comprise a dendritic-likestructure. In some embodiments, the first water-soluble macromolecule orthe second water-soluble macromolecule can have a structure comprising acombination of both linear and dendritic-like structures.

In some embodiments, the first water-soluble macromolecule and/or thesecond water-soluble macromolecular can comprise polyesters, polyethers,polyether-esters, polyester-amines, polythioesters, polyamino acids,polyurethanes, polycarbonates, polyamino alcohols, thiols, thioesters,thioester-containing polymers (e.g., thioester-containing polymersdescribed herein), crosslinking moieties (as described in detail below)such as N-hydroxysuccinimide moiety, maleimide (MAL) moiety, or anycombinations thereof.

In some embodiments, one of the first water-soluble macromolecule andthe second water-soluble macromolecule can comprise polyethylene glycol)in its backbone structure. In some embodiments, both of the firstwater-soluble macromolecule and the second water-soluble macromoleculecan comprise poly(ethylene glycol) in its backbone structure. In someembodiments, neither of the first nor the second water-solublemacromolecule comprises poly(ethylene glycol) in its backbone structure.

As used herein, the term “linear” refers to a macromolecule having abackbone that is substantially free of branching. The term“substantially free of branching” as used herein means that themacromolecule backbone is either not substituted with branches or issubstituted with no more than 3 branches per 1000 carbon atoms. The term“substantially free of branching” can also mean that the macromoleculebackbone has no more than 2, no more than 1, no more than 0.1, or nomore than 0.01 branches per 1000 carbon atoms.

The terms “branching” and “branches” as used herein refers to a sidechain comprising at least one or more carbon atoms, including, e.g., atleast two, at least three, at least four, at least five, at least six,at least seven, at least eight, at least nine, at least 10, at least 15,at least 20, at least 25, at least 50, at least 75, at least 100, ormore carbon atoms. The side chain can be linear, branched, comb-like,and dendritic-like as defined herein. The side chain can comprise one ormore (e.g., one, two, three, four or more) functional groups selectedfrom the group consisting of hydrogen, straight or branched alkyl,cycloalkyl, aryl, olefin or alkene, alkyne, silyl, alkylsilyl,arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons, fluorocarbon,and any combinations thereof, wherein each alkyl, cycloalkyl, aryl,olefin, silyl, alkylsilyl, arylsilyl, alkylaryl, fluorocarbon, orarylalkyl chain can be optionally substituted internally or terminallyby one or more hydroxyl, hydroxyether, carboxyl, carboxyester,carboxyamide, amino, mono- or di-substituted amino, thiol, thioester,sulfate, sulfonate, phosphate, phosphonate, halogen substituents, andany combinations thereof. The terms “branching” and “branches” do notinclude hydroxyl and acetate groups.

As used herein, the term “branched” refers to a macromolecule having abackbone with one or more substituent side chains or branches. Abranched macromolecule can encompass a comb-like macromolecule and adendritic-like macromolecule.

As used herein, the term “comb-like” refers to a macromolecule having abackbone with multiple trifunctional branchpoints from each of which alinear side chain or branch emanates. The linear side chain can be ofany length, e.g., comprising at least one or more carbon atoms,including, e.g., at least two, at least three, at least four, at leastfive, at least six, at least seven, at least eight, at least nine, atleast 10, at least 15, at least 20, at least 25, at least 50, at least75, at least 100, or more carbon atoms.

As used herein, the term “dendritic-like” refers to a macromolecule thatis highly branched and is generally defined by three components: acentral core or a focal point an interior dendritic structure (thebranches), and an exterior surface with functional surface groups. Thenumber of branch points increases upon moving from the central core orfocal point to its surface and defines the generation of adendritic-like macromolecule. The dendritic-like macromolecule can haveGeneration 1, Generation 2, Generation 3, Generation 4, Generation 5 ormore. The dendritic-like molecules eau encompass dendrimers, dendrons,hyperbranched polymers, and any combinations thereof.

In some embodiments, the dendritic-like macromolecules can comprise“dendrimers,” which are generally globular monodispersed macromoleculeshaving repeated branching units radially emanating from a central core.See, e.g., U.S. Pat. No. 5,714,166; U.S. Pat. No. 4,289,872; U.S. Pat.No. 4,435,548; U.S. Pat. No. 5,041,516; U.S. Pat. No. 5,362,843; U.S.Pat. No. 5,154,853; U.S. Ser. No. 05/739,256; U.S. Pat. No. 5,602,226;U.S. Pat. No. 5,514,764; Bosman, A. W.; Janssen, H. M.; Meijer, E. W.Chem. Rev. 1999, 99, 1665-1688. Fischer, M.; Vogtle, F. Angew. Chem.Int. Ed. 1999, 38, 884-905. Zeng, F.; Zimmerman, S. C. Chem. Rev. 1997,97, 1681-1712. Tomalia, D. A., Naylor, A. M.; Goddard, W. A. Angew.Chem. Int. Ed. Engl. 1990, 29, 138. These macromolecules can besynthesized using either a divergent (from core to surface) (Buhleier,W.; Wehner, F. V.; Vogtle, F. Synthesis 1987, 155-158. Tomalia, D. A.;Baker, H.; Dewald, J.; Hall, M.; Kallos, G.; Martin, S.; Roeck, J.;Ryder, J.; Smith, P. Polymer Journal 1985, 17, 117-132. Tomalia, D. A.;Baker, H.; Dewald, J.; Hall, M.; Kallos, G.; Martin, S.; Roeck, J.;Ryder, J.; Smith, P. Macromolecules 1986, 19, 2466. Newkome, G. R.; Yao,Z.; Baker, G. R.; Gupta, V. K. J. Org. Chem. 1985, 50, 2003.) or aconvergent (from surface to core) (Hawker, C. J.; Frechet, J. M. J. J.Am. Chem. Soc. 1990, 112, 7638-7647) approach. Compared to linearpolymers, dendrimers are highly ordered, possess high surface area tovolume ratios, and exhibit numerous end groups for functionalization.Thus, dendrimers display several favorable physical properties for bothindustrial and biomedical applications including: small polydispersityindexes (PDI), low viscosities, high solubility and miscibility, andadhesive properties. In some embodiments, dendrimers can includederivatives of aromatic polyether or aliphatic amides, which may not beideal for in vivo uses. (Service, R. F. Science 1995, 267, 458-459.Lindhorst, T. K.; Kieburg, C. Angew. Chem. Int. Ed. 1996, 35, 1953-1956.Ashton, P. R.; Boyd, S. E.; Brown, C. L.; Yayaraman, N.; Stoddart, J. F.Angew. Chem. Int. Ed. 1997, 1997, 732-735. Wiener, E. C.; Brechbeil, M.W.; Brothers, H.; Magin, R. L.; Gansow, O. A.; Tomalia, D. A.;Lauterbur, P. C. Magn. Reson. Med. 1994, 31, 1-8. Wiener, E. C.; Auteri,F. P.; Chen, J. W.; Brechbeil, M. W.; Gansow, O. A.; Schneider, D. S.;Beldford, R. L.; Clarkson, R. B.; Lauterbur, P. C. J. Am. Chem. Soc.1996, 118, 7774-7782. Toth, E.; Pubanz, D.; Vauthey, S.; Helm, L.;Merbach, A. E. Chem. Eur. J. 1996, 2, 1607-1615. Adam, G. A.; Neuerburg,J.; Spuntrup, E.; Muhler, A.; Scherer, K.; Gunther, R. W. J. Magn.Reson. Imag. 1994, 4, 462-466. Bourne, M. W.; Margerun, L.; Hylton, N.;Campion, B.; Lai, J. J.; Dereugin, N.; Higgins, C. B. J. Magn. Reson.Imag. 1996, 6, 305-310. Miller, A. D. Angew. Chem. Int. Ed. 1998, 37,1768-1785. Kukowska-Latallo, J. F.; Bielinska, A. U.; Johnson, J.;Spinder, R.; Tomalia, D. A.; Baker. J. R. Proc. Natl. Acad. Sci. 1996,93, 4897-4902. Hawthorne, M. F. Angew. Chem. Int. Ed. 1993, 32, 950-984.Qualmann, B.; Kessels M. M.; Musiol H.; Sierralta W. D.; Jungblut P. W.;L., M. Angew. Chem. Int. Ed. 1996, 35, 909-911). Biodendrimers are aclass of dendritic macromolecules having substantially all of thebuilding blocks known to be biocompatible or degradable to naturalmetabolites in vivo, for example, but not limited to glycerol, lacticacid, glycolic acid, succinic acid, ribose, adipic acid, malic acid,glucose, citric acid, and any combinations thereof.

In some embodiments, the dendritic-like crosslinkable polymers describedherein can comprise polyesters, polyethers, polyether-esters, andpolyamino acids, copolymers thereof, or any combinations thereof. Forexample, poly(glycolic acid), poly(lactic acid), and their copolymersare synthetic polyesters that have been approved by the FDA for certainuses, and have been used successfully as sutures, drug deliverycarriers, and tissue engineering scaffold for organ failure or tissueloss (Gilding and Reed, Polymer, 20:1459 (1979); Mooney et al., CellTranspl., 2:203 (1994); and Lewis, D. H. in Biodegradable Polymers asDrug Delivery Systems, Chasin, M., and Langer, R., Eds., Marcel Dekker,New York, 1990). Some of their advantages include their degradability inthe physiological environment to yield naturally occurring metabolicproducts and the ability to control their rate of degradation by varyingthe ratio of lactic acid. In the dendritic structures the degradationcan be controlled by both the type of monomer used and the generationnumber.

In some embodiments, the dendritic-like macromolecules can comprise“dendrons.” Dendrons are generally wedge-shaped dendrimer sections withmultiple terminal groups and a single reactive function at the focalpoint. Dendrons can undergo orthogonal reactions utilizing the focalpoint and surface groups. For example, dendrons can be conjugated toanother dendron or to another macromolecule. Examples of a dendron areshown in FIG. 1B (dendron 1); and in FIG. 2 (dendron 1 and dendron 2).

In some embodiments, the dendritic-like macromolecules can comprise“hyperbranched polymers.” Typically, hyperbranched polymers arepolydisperse dendritic macromolecules that possess dendrimer-likeproperties but are usually imperfectly branched and have an averagenumber of terminal functional groups, rather than a precise number ofterminal functional groups. These hyperbranched polymers can be preparedin single synthetic polymerization step.

In some embodiments, the crosslinkable polymers can be modified to suitthe need of an application, such as tissue engineering applications,wound management, contrast agent(s) vehicles, and drug deliveryvehicles. For example, in some embodiments, the crosslinkable polymerscan comprise a biological recognition unit for cell recognition, e.g.,but not limited to a peptide sequence and/or a growth factor. By way ofexample only, a biological recognition unit for cell recognition can beattached to the end groups or within the crosslinkable polymers. Anexample of a biological recognition unit for cell recognition includes atripeptide arginine-glycine-aspartic (RGD), which can be added to thecrosslinkable polymers, e.g., to improve interaction of the polymerswith cells, tissues, and/or bones. Barrera et al. described thesynthesis of a polylactic acid) (pLAL) containing a low concentration ofN-epsilon.-carbobenzoxy-(L)-lysine units. The polymers were chemicallymodified through reaction of the lysine units to introducearginine-glycine-aspartic acid peptide sequences or other growth factorsto improve polymer-cell interactions (Barrera et al., J. Am. Chem. Soc.,115:11010 (1993), U.S. Pat. No. 5,399,665 to Bartera et al.). In someembodiments, the crosslinkable polymers can be introduced with at leastone or more functionalities, for example, without limitations, polyaminoacids, peptides, carbohydrates, etc. in order to improve thebiocompatibility and other material properties of the polymers.

First Water-Soluble Crosslinkable Macromolecule or Polymer:

The first water-soluble macromolecule or polymer comprises at least twoor more nucleophilic moieties, including, at least about three, at leastabout four, at least about five or more nucleophilic moieties. In someembodiments, the nucleophilic moieties are selected to react with asecond-water soluble macromolecule to from a thioester hydrogel. As usedherein, the term “nucleophilic moiety” refers to an atom, a molecule ora functional group having at least one reactive pair of electrons. Anyatom, molecule or functional group with electrons available for donationto another atom, molecule or functional group, e.g., a free pair ofelectrons or at least one pi bond, can be considered as a nucleophilicmoiety. Examples of nucleophilic moieties include, without limitations,amines, thiols, alcohols, and any combinations thereof.

The nucleophilic moieties can be part of the side group or side chain ofthe first water-soluble macromolecule, the terminal group of the firstwater-soluble macromolecule, or a combination thereof. In oneembodiment, the first water-soluble macromolecule comprises at leastfour thiol moieties (as nucleophilic moieties). Alternatively, inanother embodiment, the first water-soluble macromolecule comprises atleast three amine moieties (as nucleophilic moieties). In someembodiments, the water-soluble macromolecule can also comprise at leastone or more thioester linkages that form part of the backbone structureof the macromolecule. For example, in one embodiment, the firstwater-soluble macromolecule comprises at least three amine moieties (asnucleophilic moieties), wherein the macromolecule further comprisesthioester linkages forming part of the backbone structure of themacromolecule.

The first water-soluble macromolecule or polymer comprises at least twoor more thiol moieties, including, at least about three, at least aboutfour, at least about five or more thiol moieties. The thiol moieties canbe part of the side group or side chain of the first water-solublemacromolecule, the terminal group of the first water-solublemacromolecule, or a combination thereof. In one embodiment, the firstwater-soluble macromolecule comprises at least four thiol moieties.

In some embodiments, the first water-soluble macromolecule can have achemical structure of formula (I) selected from the group consisting ofchemical structure (i)-structure (xii).

and any combinations thereof.

Q can be any atom or a group of atoms (e.g., at least two atoms or more)provided that it can form a bond (e.g., a single bond, a double bond, ora triple bond) with its neighboring atoms or groups of atoms. In someembodiments, Q can be independently selected from the group consistingof O, S, Se, NH, CH₂, and any combination thereof. In some embodiments,the first water-soluble macromolecule can comprise at least two Q atomsor groups, wherein the Q atoms or groups can be the same or differentfrom at least one of the others.

R can be any atom or a group of atoms (e.g., at least two atoms or more)provided that it can form a bond (e.g., a single bond, a double bond, ora triple bond) with its adjacent atom. R can be linear, branched,aromatic, cyclic, comb-like, or dendritic-like as defined herein. Insome embodiments, the first water-soluble macromolecule can comprise atleast two R groups, wherein the R groups can be the same or differentfrom at least one of the others. In some embodiments where at least twoR groups are in substantially the same structure, at least one R groupcan be different from another R group.

In some embodiments, R can be independently selected from the groupconsisting of a hydrogen, straight or branched alkyl, cycloalkyl, aryl,olefin or alkene, alkyne, silyl, alkylsilyl, arylsilyl, alkylaryl orarylalkyl chain of 1-50 carbons, fluorocarbon, and any combinationsthereof, wherein each alkyl, cycloalkyl, aryl, olefin, silyl,alkylsilyl, arylsilyl, alkylaryl, fluorocarbon, or arylalkyl chain canbe optionally substituted internally or terminally by one or morehydroxyl, hydroxyether, carboxyl, carboxyester, carboxyamide, amino,mono- or di-substituted amino, thiol, thioester, sulfate, phosphate,phosphonate, halogen substituents, and any combinations thereof

In some embodiments, R can comprise an oligomer or polymer of abiocompatible material, e.g., but not limited to, poly(ethylene glycol)and/or poly(ethylene oxide); poly(hydroxy acid); a carbohydrate; aprotein; a polypeptide; an amino acid; a nucleic acid; a nucleotide; apolynucleotide; a DNA segment; a RNA segment; a lipid; a polysaccharide;an antibody; a pharmaceutical agent, an epitope for a biologicalreceptor; or any combinations thereof. In some embodiments, R does notinclude poly(ethylene glycol).

In some embodiments, R can comprise an oligomer or polymer of abiocompatible material. As used herein, the term “biocompatible” refersto a material exhibiting essentially no cytotoxicity or immunogenicitywhile in contact with body fluids or tissues. The biocompatible materialcan be biodegradable or non-biodegradable. As used herein, the term“biodegradable” refers to the ability of a polymeric material to erodeor degrade in vivo to form smaller chemical fragments. Degradation mayoccur, for example, by enzymatic, chemical or physical processes.Non-limiting examples of biodegradable polymeric materials can includepolyesters, polyamides, polyethers, polycarbonates, polyanhydrides,polyorthoesters, polycaprolactone, polyesteramides, polycyanoacrylate,polyetherester, poly(phosphates), poly(phosphonates), poly(phosphites),polyhydric alcohol esters, blends and copolymers thereof. As usedherein, the term “non-biodegradable” refers to the ability of apolymeric material to resist erosion or degradation in vivo. Thus, anon-biodegradable material can stay in vivo for a significantly longamount of time, or even permanently. Non-limiting examples ofdegradation-resistant polymeric materials can include polyethylene,polypropylene, polytetrafluoroethylene, polyurethanes, silicon,polyacrylates, ethylene-vinyl acetates (and other acyl-substitutedcellulose acetates), polystyrenes, polyvinyl oxides, polyvinylfluorides, poly(vinyl imidazoles), chlorosulphonated polyolefins,polyethylene oxides, polyvinyl alcohols (PVA), any art-recognizeddegradation-resistant polymers, or any combinations thereof.

In one embodiment, R can comprise poly(ethylene glycol) and/orpoly(ethylene oxide);

m, n, x, and y can each independently be any integer of zero or greater(e.g., at least one or more) provided that the first water-solublemacromolecule has a molecular weight of at least about 200 Da or more(e.g., at least about 1 kDa, at least about 2 kDa or more) and can reactwith the second water-soluble macromolecule to form a gel. For example,m, n, x, and y can each independently be an integer of 0 or greater,including, e.g., at least one, at least two, at least three, at leastfour, at least five, at least six, at least seven, at least eight, atleast nine, at least 10, at least 20, at least 25, at least 50, at least75, at least 100, at least 250, at least 500, at least 750, at least1000, at least 1500 or more. In some embodiments, m, n, x, and y caneach be independently selected from an integer of 1-1000, or from aninteger of 10-1000.

In some embodiments, the first water-soluble macromolecule can be adendritic-like macromolecule as defined herein. In one embodiment, thefirst water-soluble macromolecule can be a dendron.

In one embodiment, the first water-soluble macromolecule has a chemicalstructure of formula (II), wherein the formula (II) is represented asfollows:

Additionally or alternatively, the first water-soluble macromolecule cancomprise at least two thioester linkages or more, including, at leastabout three, at least about four, at least about five or more thioesterlinkages. In one embodiment, the first water-soluble macromoleculecomprises at least three or more thioester moieties. The thioesterlinkages can form part of the backbone structure of the firstwater-soluble macromolecule. For example, the first water-solublemacromolecule can have a chemical structure of formula (III), whereinthe formula (III) is represented as follows:

Synthesis of the first water-soluble macromolecule of formula (III) fromcitric acid is described in Example 6.

In some embodiments, the first water-soluble macromolecule comprises atleast two or more nucleophilic moieties (e.g., but not limited to thiol,amine, alcohol), including at least about three, at least about four, atleast about five or more nucleophilic moieties, that can react with asecond-water soluble macromolecule that contains at least two or morethioester linkages to from a thioester hydrogel. For example, the firstand the second-water soluble macromolecules can have chemical structuresof formula (IV) and (V), respectively, wherein the formula (IV) and (V)are represented as follows:

Syntheses of the first and second water-soluble macromolecules offormula (IV) and (V) are described in Examples 1 and 8, respectively.

Second Water-Soluble Macromolecule Comprising at Least Two CrosslinkingMoieties:

In some embodiments, the second water-soluble macromolecule comprises atleast two crosslinking moieties that can form a linkage with thenucleophilic moieties of the first water-soluble macromolecule to enableformation of a thioester hydrogel comprising at least two thioesterbonds (—S—C═O—). In some embodiments, the second water-solublemacromolecule comprises at least two crosslinking moieties that canreact with the thiol moieties (—SH) of the first water-solublemacromolecule to enable formation of a thioester hydrogel comprising atleast two thioester bonds (—S—C═O—). For example, the secondwater-soluble macromolecule can comprise at least two or morecrosslinking moieties, including, at least about three, at least aboutfour, at least about five or more crosslinking moieties. Thecrosslinking moieties can be part of the side group or side chain of thesecond water-soluble macromolecule, the terminal group of the secondwater-soluble macromolecule, or a combination thereof. In oneembodiment, the second water-soluble macromolecule comprises at leasttwo crosslinking moieties.

As used herein, the term “crosslinking moiety” or “crosslinkingmoieties” refers to an organic reactive atom or group of atoms (e.g., agroup of at least two or more atoms) that can react with thenucleophilic moieties (e.g., but not limited to thiol (—SH), alcohol(—OH), amine (—NH₂) of the first water-soluble macromolecule. The secondwater-soluble macromolecule can comprise any art-recognized crosslinkingmoieties, e.g., but not limited to,1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC orEDAC), hydroxybenzotriazole (HOBT), N-Hydroxysuccinimide (NHS),N-Hydroxysuccinimide ester (NHS ester), imidoester, maleimide,haloacetyl (e.g., iodoacetyl or bromoacetyl), hydrazide, alkoxyamine,photoreactive crosslinking moieties (e.g., but not limited to phenylazide, and diazirine), 2-(1H-7-Azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate methanaminium (HATU), silanization, alkylhalide, aldehyde, amino, bromo or iodoacetyl, carboxyl, hydroxyl, epoxy,ester, silane, and any combinations thereof.

In some embodiments, at least one of the crosslinking moieties of thesecond water-soluble macromolecule can comprise a N-Hydroxysuccinimide(NHS) moiety. In some embodiments, the second water-solublemacromolecule can further comprise at least two thioester linkageswithin the backbone structure of the macromolecule.

In some embodiments, at least one of the crosslinking moieties of thesecond water-soluble macromolecule can comprise a maleimide (MAL)moiety. In some embodiments, the second water-soluble macromolecule canfurther comprise at least two thioester linkages within the backbonestructure of the macromolecule.

In some embodiments, at least one of the crosslinking moieties of thesecond water-soluble macromolecule can comprise N-Hydroxysuccinimide(NHS) and/or maleimide (MAL) moieties. In some embodiments, the secondwater-soluble macromolecule can further comprise at least two thioesterlinkages within the backbone structure of the macromolecule.

In some embodiments, at least one of the crosslinking moieties of thesecond water-soluble macromolecule can comprise a NHS ester, e.g., butnot limited to succinimidyl valerate (SVA), succinimidyl carbonate (SC),succinimidyl glutarate (SG), succinimidyl succinate (SS), succinimidylcarboxymethyl (SCM), succinimidyl propionate (SPA), and any combinationsthereof. In one embodiment, at least one of the crosslinking moieties ofthe second water-soluble macromolecule comprises a succinimidylvalerate.

In some embodiments, the second water-soluble macromolecule can have achemical structure of formula (VI) selected from the group consisting ofchemical structures (xiii)-(xl).

and any combinations thereof.

Q can be any atom or a group of atoms (e.g., at least two atoms or more)provided that it can form a bond (e.g., a single bond, a double bond, ora triple bond) with its neighboring atoms or groups of atoms. In someembodiments, Q can be independently selected from the group consistingof O, S, Se, NH, CH₂, and any combination thereof. In some embodiments,the second water-soluble macromolecule can comprise at least two Q atomsor groups, wherein the Q atoms or groups can be the same or differentfrom at least one of the others.

R can be any atom or a group of atoms (e.g., at least two atoms or more)provided that it can form a bond (e.g., a single bond, a double bond, ora triple bond) with its adjacent atom. R can be linear, branched,aromatic, cyclic, comb-like, or dendritic-like as defined herein. Insome embodiments, the second water-soluble macromolecule can comprise atleast two R groups, wherein the R groups can be the same or differentfrom at least one of the others. In some embodiments where at least twoR groups are in substantially the same structure, at least one R groupcan be different from another R group.

In some embodiments, R can be independently selected from the groupconsisting of a hydrogen, straight or branched alkyl, cycloalkyl, aryl,olefin or alkene, alkyne, silyl, alkylsilyl, arylsilyl, alkylaryl orarylalkyl chain of 1-50 carbons, fluorocarbon, and any combinationsthereof, wherein each alkyl, cycloalkyl, aryl, olefin, silyl,alkylsilyl, arylsilyl, alkylaryl, fluorocarbon, or arylalkyl chain canbe optionally substituted internally or terminally by one or morehydroxyl, hydroxyether, carboxyl, carboxyester, carboxyamide, amino,mono- or di-substituted amino, thiol, thioester, sulfate, phosphate,phosphonate, halogen substituents; and any combinations thereof.

In some embodiments, R can comprise an oligomer or polymer of abiocompatible material, e.g., but not limited to, poly(ethylene glycol)and/or poly(ethylene oxide); poly(hydroxy acid); a carbohydrate; aprotein; a polypeptide; an amino acid; a nucleic acid; a nucleotide; apolynucleotide; a DNA segment; a RNA segment; a lipid; a polysaccharide;an antibody; a pharmaceutical agent, an epitope for a biologicalreceptor; or any combinations thereof.

m, n, x, y, and z can each independently be any integer of 0 or greater(e.g., at least 1 or greater) provided that the first water-solublemacromolecule has a molecular weight of at least about 200 Da or more(e.g., at least about 1 kDa, at least about 2 kDa or more) and can reactwith the first water-soluble macromolecule to form a gel. For example,m, n, x, y, and z can each independently be an integer of zero orgreater, including, e.g., at least one, at least two, at least three, atleast four, at least five, at least six, at least seven, at least eight,at least nine, at least 10, at least 20, at least 25, at least 50, atleast 75, at least 100, at least 250, at least 500, at least 750, atleast 1000, at least 1500 or more. In some embodiments, m, n, x, y, andz can each be independently selected from an integer of 1-1000, or froman integer of 10-1000.

In some embodiments, the second water-soluble macromolecule can be alinear macromolecule as defined herein. For example, in someembodiments, the second water-soluble macromolecule can have thefollowing chemical structure (xiii), wherein R is hydrogen:

In these embodiments, Q can be oxygen. In these embodiments, x can be aninteger of four. In one embodiment, the second water-solublemacromolecule is poly(ethylene glycol) disuccinimidyl valerate, e.g.,with a molecular weight of about 3400 Da. The molecular weight of thepoly(ethylene glycol) disuccinimidyl valerate can vary with the chainlength of the poly(ethylene glycol).

In some embodiments, the second water-soluble macromolecule can have achemical structure of formula (V) shown as follows:

In some embodiments, the second water-soluble macromolecule can have achemical structure of formula (VII) shown as follows:

In some embodiments, the thioester hydrogel described herein can beentirely or partially flexible. As used herein, the term “flexible”generally refers to a material being capable of bending or flexing suchthat it is pliant and yieldable in response to a change in surroundingcondition (e.g., an external force or pressure), without causing anymacroscopic breaking. A flexible material can generally alter geometricshape and/or volume to accommodate a change in surrounding conditionand/or to conform to the shape of an object brought in contact with itwithout losing its integrity. Thus, the term “flexible” when used inreference to the thioester hydrogel described herein refers to ahydrogel being capable of swelling without losing its integrity when itis exposed to an aqueous condition and/or being conformal to the shapeof a surface or void to which the thioester hydrogel is applied.

In some embodiments, the thioester hydrogel described herein can becapable of withstanding a fluid pressure of at least about 2 mmHg,including, e.g., at least about 5 mmHg, at least about 10 mmHg, at leastabout 20 mmHg, at least about 30 mmHg, at least about 40 mmHg, at leastabout 50 mmHg, at least about 60 mmHg, at least about 70 mmHg, at leastabout 80 mmHg, including, e.g., at least about 90 mmHg, at least about100 mmHg, at least about 150 mmHg, at least about 200 mmHg, at leastabout 250 mmHg, at least about 300 mmHg, at least about 350 mmHg ormore. In some embodiments, the thioester hydrogel when used as a sealantin a blood vessel can withstand an arterial pressure of at least about80 mmHg, at least about 100 mmHg, at least about 120 mmHg, at leastabout 150 mmHg, at least about 200 mmHg. Thioester hydrogels can beadapted for various mechanical strengths to provide appropriatetreatment of different types of wounds.

In some embodiments, the thioester hydrogel described herein can betransparent. The term “transparent” as used herein refers to a hydrogelmaterial which can transmit an average of greater than 30% or more(including, e.g., greater than 40%, greater than 50%, greater than 60%,greater than 70%, greater than 80%, greater than 90%, greater than 95%or more) of incident visible light across the visible light spectrum.

In some embodiments, the thioester hydrogels described herein arehydrophilic. As used herein, the term “hydrophilic” in reference to ahydrogel means that the hydrogel can interact with water molecules byelectrostatic interaction and/or hydrogen bonds. For example, ahydrophilic hydrogel can attract and absorb water from a surroundingenvironment and swell to a larger volume. A hydrophilic hydrogel can bewater-soluble or water-insoluble. In accordance with embodiments ofvarious aspects described herein, the thioester hydrogel can bedissolved in an aqueous solution comprising a thiolate compound, butremain hydrolytically stable in water or a salt solution at a pH valuein a range from about 3 to at least about 9. Hydrophilicity of thehydrogel can, in part, depend on the hydrophilicity of the crosslinkablepolymers that form the hydrogel. In some embodiments, a hydrophilicthioester hydrogel is a hydrogel comprising hydrophilic crosslinkablepolymers, e.g., crosslinkable polymers comprising polar and/or chargedfunctional groups, rending them to soluble in water. Examples ofhydrophilic crosslinkable polymers can include, but are not limited to,poly(ethylene glycol), poly(ethylene oxide), poly(glycerol), poly(vinylacetate), poly(vinyl pyrrolidone), poly(propylene glycol), poly(vinylalcohol), polysiloxane, maleic anhydride copolymers, polyethers,copolymers thereof, and any combinations thereof.

In some embodiments, the thioester hydrogel described herein can beelastic. As used herein, the term “elastic” refers to a hydrogel havinglow Young's modulus and high yield strain compared with other types ofpolymeric materials.

In some embodiments, the thioester hydrogel described herein can beviscoelastic. As used herein, the term “viscoelastic” refers to ahydrogel exhibiting both elastic and viscous characteristics. Forexample, a viscoelastic hydrogel can at least partially return to itsoriginal form when an applied stress is released, and the response istime-dependent. In dynamic mechanical characterization, the level ofviscoelasticity is proportional to the damping coefficient measured bythe tan (delta) of the material. The tan (delta) is generally the ratioof the viscous dissipative loss modulus to the elastic storage modulus.High tan (delta) values can indicate a high viscous component in thematerial behavior and hence a strong damping to any perturbation will beobserved. The measurement of these moduli is described in AnIntroduction to Rheology, by Barnes, H. A., Hutton, J. F., and Walters,K.; Elsevier, Amsterdam (1997).

In some embodiments, the thioester hydrogels described herein are atleast 50% or more mechanically stronger than a disulfide-crosslinkedhydrogel (e.g., 8-arm-PEG-SH (20 kDa)) described in Sinko, P. J. et al.Biomaterials, 2011, 32, 1204-1217) of the same weight percent. Forexample, in one embodiment, the ˜10 wt % thioester hydrogel describedherein has a storage modulus of about 6000 Pa, while a ˜10 wt %disulfide-crosslinked hydrogel has a storage modulus of about 3000 Pa.In some embodiments, the thioester hydrogel described herein can have astorage modulus of at least about 3000 Pa or higher, including, e.g., atleast about 4000 Pa, at least about 5000 Pa, at least about 6000 Pa, atleast about 7000 Pa, at least about 8000 Pa, at least about 9000 Pa, atleast about 10000 Pa, at least about 20000 Pa, at least about 30000 Pa,at least about 40000 Pa or higher.

The thioester hydrogel can form any shape, e.g., a film, a sheet, acoating, or a three-dimensional construct, e.g., a hollow and/or solidstructure. In some embodiments, the thioester hydrogel can form a film,a sheet, a coating, or a layer and termed as “dissolvable hydrogellayer” herein.

In some embodiments, the thioester hydrogel can further comprise atleast one or more bioactive agents described herein. In someembodiments, the thioester hydrogel can further comprise at least two ormore, including, e.g., 2, 3, 4, 5, 6 or more bioactive agents describedherein.

Definitions of some chemical functional groups used herein are definedas follows. As used herein, the term “alkyl” refers to an aliphatichydrocarbon group which can be straight or branched having one to about60 carbon atoms in the chain, and which preferably have about six toabout 50 carbons in the chain. “Lower alkyl” refers to an alkyl grouphaving one to about nine carbon atoms. “Higher alkyl” refers to an alkylgroup having about 10 to about 20 carbon atoms. The alkyl group can beoptionally substituted with one or more alkyl group substituents whichcan be the same or different, where “alkyl group substituent” includeshalo, amino, aryl, hydroxy, alkoxy, aryloxy, alkyloxy, alkylthio,arylthio, aralkyloxy, aralkylthio, carboxy, alkoxycarbonyl, oxo andcycloalkyl. There can be optionally inserted along the alkyl chain oneor more oxygen, silicon, sulfur, or substituted or unsubstitutednitrogen atoms, wherein the nitrogen substituent is lower alkyl.“Branched” when used in reference to an alkyl group means an alkyl groupin which a lower alkyl group, such as methyl, ethyl or propyl, isattached to a linear alkyl chain. Exemplary alkyl groups include methyl,ethyl, i-propyl, n-butyl, t-butyl, n-pentyl, heptyl, octyl, decyl,dodecyl, tridecyl, tetradecyl, pentadecyl and hexadecyl. Useful alkylgroups include branched or straight chain alkyl groups of six to 50carbon, and also include the lower alkyl groups of one to about fourcarbons and the higher alkyl groups of about 12 to about 16 carbons.

As used herein, the term “alkenyl” or “alkene” refers to an alkyl groupcontaining at least one carbon-carbon double bond. The alkenyl group canbe optionally substituted with one or more “alkyl group substituents.”Exemplary alkenyl groups include vinyl, allyl, n-pentenyl, decenyl,dodecenyl, tetradecadienyl, heptadec-8-en-1-yl andheptadec-8,11-dien-1-yl.

As used herein, the term “alkynyl” or “alkyne” refers to an alkyl groupcontaining a carbon-carbon triple bond. The alkyne group can beoptionally substituted with one or more “alkyl group substituents.”Exemplary alkynyl groups include ethynyl, propargyl, n-pentynyl, decynyland dodecynyl. Useful alkynyl groups include the lower alkynyl groups.

As used herein, the term “cycloalkyl” refers to a non-aromatic mono- ormulticyclic ring system of about four to about 10 carbon atoms. Thecycloalkyl group can be optionally partially unsaturated. The cycloalkylgroup can be also optionally substituted with an aryl group substituent,oxo and/or alkylene. Representative monocyclic cycloalkyl rings includecyclopentyl, cyclohexyl and cycloheptyl. Useful multicyclic cycloalkylrings include adamantyl, octahydronaphthyl, decalin, camphor, camphane,and noradamantyl.

As used herein, the term “aryl” refers to an aromatic carbocyclicradical containing about 6 to about 10 carbon atoms. The aryl group canbe optionally substituted with one or more aryl group substituents,which can be the same or different, where “aryl group substituent”includes alkyl, alkenyl, alkynyl, aryl, aralkyl, hydroxy, alkoxy,aryloxy, aralkoxy, carboxy, aroyl, halo, nitro, trihalomethyl, cyano,alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, acyloxy, acylamino,aroylamino, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, rylthio,alkylthio, alkylene and —NRR′, where R and R′ are each independentlyhydrogen, alkyl, aryl and aralkyl. Exemplary aryl groups includesubstituted or unsubstituted phenyl and substituted or unsubstitutednaphthyl.

As used herein, the term “acyl” refers to an alkyl-CO— group, whereinalkyl is as previously described. Exemplary acyl groups comprise alkylof 1 to about 30 carbon atoms. Exemplary acyl groups also includeacetyl, propanoyl, 2-methylpropanoyl, butanoyl and palmitoyl.

As used herein, the term “aroyl” means an aryl-CO— group, wherein arylis as previously described. Exemplary aroyl groups include benzoyl and1- and 2-naphthoyl.

As used herein, the term “alkoxy” refers to an alkyl-O— group, whereinalkyl is as previously described. Exemplary alkoxy groups includemethoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, and heptoxy.

As used herein, the term “aryloxy” refers to an aryl-O— group, whereinthe aryl group is as previously described. Exemplary aryloxy groupsinclude phenoxy and naphthoxy.

As used herein, the term “alkylthio” refers to an alkyl-S— group,wherein alkyl is as previously described. Exemplary alkylthio groupsinclude methylthio, ethylthio, i-propylthio and heptylthio.

As used herein, the term “arylthio” refers to an aryl-S— group, whereinthe aryl group is as previously described. Exemplary arylthio groupsinclude phenylthio and naphthylthio.

As used herein, the term “aralkyl” refers to an aryl-alkyl-group,wherein aryl and alkyl are as previously described. Exemplary aralkylgroups include benzyl, phenylethyl and naphthylmethyl.

As used herein, the term “aralkyloxy” refers to an aralkyl-O— group,wherein the aralkyl group is as previously described. An exemplaryaralkyloxy group is benzyloxy.

As used herein, the term “aralkylthio” refers to an aralkyl-S— group,wherein the aralkyl group is as previously described. An exemplaryaralkylthio group is benzylthio.

As used herein, the term “dialkylamino” refers to an —NR′R″ group,wherein each of R′ and R″ is independently an alkyl group as previouslydescribed. Exemplary alkylamino groups include ethylmethylamino,dimethylamino, and diethylamino.

As used herein, the term “alkoxycarbonyl” refers to an alkyl-O—CO—group. Exemplary alkoxycarbonyl groups include methoxycarbonyl,ethoxycarbonyl, butyloxycarbonyl, and t-butyloxycarbonyl.

As used herein, the term “aryloxycarbonyl” refers to an aryl-O—CO—group. Exemplary aryloxycarbonyl groups include phenoxy- andnaphthoxy-carbonyl.

As used herein, the term “aralkoxycarbonyl” refers to an aralkyl-O—CO—group. An exemplary aralkoxycarbonyl group is benzyloxycarbonyl.

As used herein, the term “carbamoyl” refers to an H₂N—CO— group.

As used herein, the term “alkylcarbamoyl” refers to a R′R″N—CO— group,wherein one of R″ and R′ is hydrogen and the other of R″ and R′ is alkylas previously described.

As used herein, the term “dialkylcarbamoyl” refers to R′R″N—CO— group,wherein each of R″ and R′ is independently alkyl as previouslydescribed.

As used herein, the term “acyloxy” refers to an acyl-O— group, whereinacyl is as previously described.

As used herein, the term “acylamino” refers to an acyl-NH— group,wherein acyl is as previously described.

As used herein, the term “aroylamino” refers to an aroyl-NH— group,wherein aroyl is as previously described.

As used herein, the term “alkylene” refers to a straight or branchedbivalent aliphatic hydrocarbon group having from one to about 30 carbonatoms. The alkylene group can be straight, branched, or cyclic. Thealkylene group can be also optionally unsaturated and/or substitutedwith one or more “alkyl group substituents.” There can be optionallyinserted along the alkylene group one or more oxygen, sulphur, orsubstituted or unsubstituted nitrogen atoms, wherein the nitrogensubstituent is alkyl as previously described. Exemplary alkylene groupsinclude methylene (—CH2-), ethylene (—CH2-CH2-), propylene (—(CH2)3-),cyclohexylene (—C6H10-), —CH═CH—CH═CH—, —CH═CH—CH2-, —(CF2)n(CH2)m-,wherein n is an integer from about 1 to about 50 and m is an integerfrom zero to about 50, —(CH2)n-N(R)—(CH2)m-, wherein each of m and n isindependently an integer from zero to about 50 and R is hydrogen oralkyl, methylenedioxy CH2-O—) and ethylenedioxy (—O—(CH2)2-O—). Analkylene group can have about two to about three carbon atoms and canfurther have 6-50 carbons.

As used herein, the term “halo” or “halide” refers to fluoride,chloride, bromide, or iodide.

As used herein, the term “fluorocarbon” includes fluoroalkyl,fluorocycloalkyl, and fluoroether groups.

As used herein, the term “silyl” refers to hydrocarbyl derivatives ofthe silyl group: R′₃Si, wherein R′ can be hydrogen, alkyl, aryl, or anycombinations thereof.

Dissolvable Hydrogel Compositions Comprising a Dissolvable HydrogelLayer Described Herein

In another aspect, provided herein relates to a dissolvable hydrogelcomposition comprising at least one layer of the dissolvable hydrogeldescribed herein. In some embodiments, the dissolvable hydrogel layercan function as an adhesive layer, allowing the dissolvable hydrogelcomposition to adhere to a surface (e.g., a tissue surrounding a wound)and be controllably removed from the tissue surface, when needed at alater time, by addition of a thiolate compound. In some embodiments, thedissolvable hydrogel layer can further comprise a bioactive agentdescribed herein that can be released from the hydrogel layer to theadhered tissue. Examples of bioactive agents can include, but are notlimited to, pharmaceutical agents, drugs, cells, gases and gaseousprecursors, synthetic organic molecules, proteins, enzymes, growthfactors, vitamins, steroids, polyanions, nucleosides, nucleotides,polynucleotides, nanoparticles, diagnostic agents, genetic materials,and any combinations thereof. Additional information about bioactiveagents is described below in section “Bioactive agents.”

In some embodiments, the dissolvable hydrogel composition can be presentas a thin sheet or layer. In some embodiments, the dissolvable hydrogelcomposition can be present as a thin sheet or layer supported by a sheetsupport member to provide mechanical strength. The sheet support memberfor the hydrogel can, for example, be a thin scrim or net structure, forexample formed of a synthetic and/or natural polymer such aspolyethylene or polypropylene. The sheet support member for thedissolvable hydrogel can be disposed on the surface of the dissolvablehydrogel composition that is directed away from a surface (e.g., a woundor lesion) in use. Alternatively or additionally, the sheet supportmember can be embedded within the hydrogel polymer. The sheet supportmember can, if desired, extend beyond the margins of the hydrogelcomposition, and can be provided with a skin-adhesive portion to furthersecure the dissolvable hydrogel composition to the skin. Theskin-adhesive portion can be hydrogel in nature (for example aplasticized tacky hydrogel, which can be the same as or different fromthe hydrogel provided on the support member), or may be another type ofskin adhesive selected from the many skin adhesives known in the wounddressings art. The support member can be or can comprise a sheet memberas defined in WO 2007/113452, the content of which is incorporatedherein by reference. In some embodiments, the support member cancomprise or be a “fibrous absorbent sheet member” as defined in WO2007/113452 and/or can comprise one or more other sheet members definedas “other absorbent sheet members” in WO 2007/113452.

In some embodiments, the dissolvable hydrogel composition can be amulti-layer composite comprising at least one layer of the dissolvablehydrogel described herein and at least one additional layer such asadditional hydrogel layer(s), and/or other polymer(s), and/or othersheet support members. By way of example only, in some embodiments, amulti-layer hydrogel composition can comprise at least one layer of thedissolvable hydrogel described herein overlaid by at least one or moredrug-releasing layers and/or a breathable (air and/or moisturepermeable) polymeric film (e.g., but not limited to, polyurethane film)as the top layer. The drug-releasing layer(s) can comprise apharmaceutically active agent described herein entrapped in a hydrogeland/or polymeric matrix. The pharmaceutically active agent can bephysically entrapped in the hydrogel and/or polymeric matrix, and/orconjugated to matrix-forming monomers that form the hydrogel and/orpolymeric matrix.

In some embodiments, the dissolvable hydrogel composition can beprovided with a protectant layer (e.g. of non-stick paper or plastic,such as siliconised paper or plastic) to protect one or both surfaces ofthe hydrogel composition prior to use.

While not necessary, in some embodiments, the dissolvable hydrogelcomposition can further comprise a degradable or non-degradable mesh tobe used in combination with the dissolvable hydrogel to provideadditional adhesion to a tissue site. Further, the combination of themesh and the dissolvable hydrogel layer can provide for improvedstrength, which can be desirable when the area of tissue repair islarge, such as a tissue plane or a hernie repair.

Meshes to be used in combination with the dissolvable hydrogel layerinclude, but are not limited to, commercially available products.Examples of films and meshes include INTERCEED (Johnson & Johnson,Inc.), PRECLUDE (W.L. Gore), and POLYACTIVE (poly(ether ester)multiblock copolymers (Osteotech, Inc., Shrewsbury, N.J.), based onpoly(ethylene glycol) and poly(butylene terephthalate), and SURGICALabsorbable hemostat gauze-like sheet from Johnson & Johnson. Anothermesh is a prosthetic polypropylene mesh with a bioresorbable coatingcalled SEPRAMESH Biosurgical Composite (Genzyme Corporation, Cambridge,Mass.). One side of the mesh is coated with a bioresorbable layer ofsodium hyaluronate and carboxymethylcellulose, providing a temporaryphysical barrier that separates the underlying tissue and organ surfacesfrom the mesh. The other side of the mesh is uncoated, allowing forcomplete tissue ingrowth similar to bare polypropylene mesh. In oneembodiment, the fibrosis-inducing agent may be applied only to theuncoated side of SEPRAMESH and not to the sodiumhyaluronate/carboxymethylcellulose coated side. Other films and meshesinclude: (a) BARD MARLEX mesh (C.R. Bard, Inc.), which is a very denseknitted fabric structure with low porosity; (b) monofilamentpolypropylene mesh such as PROLENE available from Ethicon, Inc.Somerville, N.J. (sec, e.g., U.S. Pat. Nos. 5,634,931 and 5,824,082));(c) SURGISIS GOLD and SURGISIS IHM soft tissue graft (both from CookSurgical, Inc.) which are devices specifically configured for use toreinforce soft tissue in repair of inguinal hernias in open andlaparoscopic procedures; (d) thin walled polypropylene surgical meshessuch as are available from Atrium Medical Corporation (Hudson, N.H.)under the trade names PROLITE, PROLITE ULTRA, and LITEMESH; (e) COMPOSIXhernia mesh (C.R. Bard, Murray Hill, N.J.), which incorporates a meshpatch (the patch includes two layers of an inert synthetic mesh,generally made of polypropylene, and is described in U.S. Pat. No.6,280,453) that includes a filament to stiffen and maintain the devicein a flat configuration; (f) VISILEX mesh (from C.R. Bard, Inc.), whichis a polypropylene mesh that is constructed with monofilamentpolypropylene; (g) other meshes available from C.R. Bard, Inc. whichinclude PERFIX Plug, KUGEL Hernia Patch, 3D MAX mesh, LHI mesh, DULEXmesh, and the VENTRALEX Hernia Patch; and (h) other types ofpolypropylene monofilament hernia mesh and plug products include HERTRAmesh 1, 2, and 2A, HERMESH 3, 4 & 5 and HERNIAMESH plugs T1, T2, and T3from Herniamesh USA, Inc. (Great Neck, N.Y.).

In some embodiments, the dissolvable hydrogel composition can constitutea dressing, bandage, glue, sealant, coating, and/or covering for awound, tissue void or lesion. The dissolvable hydrogel composition can,after removal of any protectant layer as appropriate, be applied to thewound directly so that the dissolvable hydrogel layer can adhere totissue surrounding the wound, thus contacting and/or protecting thewound and surrounding tissues. While not necessary, in some embodiments,additional conventional bandages, cloths or other protective fabrics ormaterials can be subsequently applied to further encase the dissolvablehydrogel composition.

In some embodiments, these compositions can be formulated to treat,seal, and/or adhere various tissues, for example, but not limited to,dura mater, cardiovascular tissue, ducts, bladders, lung tissue, liver,other parenchymal organs, bones, skeletal muscles, skin, as well as softtissues. In some embodiments, these compositions can be formulated totreat patients suffering from a variety of internal or topicalconditions, including, but not limited to, lacerations, tears, wounds,ulcers, astamoses, and surgical procedures. In some embodiments, thecompositions can be formulated for use in any indication or applicationwhere a suture or staple is being used. In some embodiments, thedissolvable hydrogel composition can be formulated to form a sealantand/or glue for use where the site of the wound is not easily accessibleor where sutureless surgery is desired, including, e.g., but not limitedto urinary tract surgery (e.g., nephrotomy closure, urethral repair,hypospadia repair), pulmonary surgery (e.g., sealing parenchymal &bronchial leaks, bronchopleural fistula repair, persistent air leakrepairs), gastrointestinal tract and stomach surgery (e.g., parotidcutaneous fistula, tracheo-oesophageal fistula, peptic ulcer repair),joint surgery (e.g., cartilage repair, meniscal repair), heart surgery(e.g., cardiac ventricular rupture repair), brain surgery (e.g., duraldefect repairs), ear surgery (e.g., ear drum perforation), andpost-surgical drainage reduction (e.g., mastectomy, axillarydissection). The ease of application, as well as the ability to quicklyform a gel to seal a wet or dry wound, and the ability to dissolve uponaddition of a thiolate compound, if needed, to release the hydrogelcomposition at a later time point from the wound can provide bettermanagement of a wound (e.g., delicate tissue) without any furtherunnecessary tissue damage and can thus promote wound healing.

In some embodiments, the dissolvable hydrogel composition can beformulated to form a cell construct or scaffold or matrix or gel, e.g.,for organ/tissue repair or replacement. In these embodiments, thedissolvable hydrogel composition can further comprise cells. The cellscan be incorporated into the dissolvable hydrogel layer and/oradditional layers such as additional hydrogel layer(s) and/or polymermatrices, if any.

By way of example only, islets of Langerhans (the insulin producingcells of the pancreas) can be embedded in the dissolvable hydrogeland/or the dissolvable hydrogel composition, which can then betransplanted into a subject to regulate blood sugar level in a diabeticsubject. Accordingly, microencapsulation of tissue-specific cells intothe dissolvable hydrogel and/or the dissolvable hydrogel composition canbe used to treat a number of disease states, e.g., due to celldysfunction, including, but not limited to, Parkinson's disease (e.g.,L-dopamine cells), liver disease (e.g., hepatocyte cells), and diabetes(e.g., islets of Langerhans).

Additional examples of cells that can be incorporated in the dissolvablehydrogel composition include but are not limited to hepatocytes and bileduct cells, islet cells of the pancreas, parathyroid cells, thyroidcells, cells of the adrenal-hypothalmic-pituitary axis includinghormone-producing gonadal cells, epithelial cells, nerve cells, heartmuscle cells, blood vessel cells, lymphatic vessel cells, kidney cells,and intestinal cells, cells forming bone and cartilage, smooth andskeletal muscle. Besides these types of cells, stem cells and/or derivedstem cells (e.g., induced pluripotent stem cells) can also be used inthe dissolvable hydrogel composition. For example, stem cells and/orderived stem cells can be incorporated in the dissolvable hydrogelcomposition and be subsequently converted to a desired specific celltype according to methods known in the art. The cells can be obtainedfrom a patient's body (autologous cells), from a donor (allogeneiccells) and/or from established cell lines.

In some embodiments, the dissolvable hydrogel composition can beformulated to form temporary scaffolding, e.g., for cellular growth(e.g., in vitro, in vivo, and in situ) and implantation. The dissolvablehydrogel composition or the dissolvable hydrogel can be formed prior toimplantation or in situ by crosslinking the crosslinkable polymers. Thedissolvable hydrogel composition or the dissolvable hydrogel can adhereto the tissue after implantation, thus preventing the dissolvablehydrogel composition or the dissolvable hydrogel from moving away fromthe implanted site over time and allowing cells to adhere to thehydrogel for cellular growth and/or tissue regeneration. The dissolvablehydrogel or the dissolvable hydrogel composition as a temporaryscaffolding can then be dissolved by addition of a thiolate compound atan appropriate time, e.g., after there is sufficient cellular growthwithin the hydrogel and/or tissue integration with the dissolvablehydrogel composition or the dissolvable hydrogel. In some embodiments,the dissolvable hydrogel composition can further comprise a bioactiveagent described herein, e.g., but not limited to angiogenesis-inducingfactors (e.g., vascular endothelial growth factors) and/ordifferentiation factors, to enhance vascularization and/ordifferentiation of the growing cell mass following implantation.

In some embodiments, the crosslinkable polymers used to form thedissolvable hydrogel described herein can have pendent heteroatom and/orfunctional groups (e.g., but not limited to amine, carboxylic acid) thatallow control of physical properties, derivatization of the polymerswith at least one bioactive agent, e.g., but not limited to a drug,and/or alteration of the biodegradability of the polymers. In someembodiments, a dissolvable hydrogel composition can form a long or ashort-term implantable medical device. In some embodiments, thecomposition can further comprise a biologically and/or pharmaceuticallyactive agent described herein (e.g., but not limited to, drugs,peptides, nucleic acids, and small molecules) sufficient for effectivesite-specific or systemic drug delivery (Gutowska et al., J. Biomater.Res., 29, 811-21 (1995) and Hoffman, J. Controlled Release, 6, 297-305(1987)). The biologically and/or pharmaceutically active agents can bephysically mixed, embedded in, dispersed in, covalently attached, oradhered to the hydrogel matrix and/or the crosslinkable polymers thatform the hydrogel matrix by covalent interaction (e.g., but not limitedto, hydrogen bonds) or non-covalent interaction (e.g., van der Waalsinteraction, electrostatic interaction, physical adsorption, and/orphysical entrapment). When biologically and/or pharmaceutically activeagent(s) described herein is attached to the hydrogel matrix and/or thecrosslinkable polymers that form the hydrogel matrix by covalent bonds,sustained release of the active agent can be provided by means ofhydrolysis of the covalent bond between the active agent and the polymerbackbone as well as by the site of the active agent in the hydrogelstructure (e.g., interior vs. exterior). In some embodiments, thependent groups on the hydrogel structure can be pH sensitive such ascarboxylic acid groups which further controls the pH dependentdissolution rate.

In some embodiments of various aspects described herein, the dissolvablehydrogels (or the dissolvable hydrogel layers) as described herein canbe used with vacuum assisted closure. Vacuum assisted closure (alsoknown as vacuum therapy, vacuum sealing or negative pressure woundtherapy) generally employs vacuum assisted drainage to remove bloodand/or serous fluid from a wound, burn area or operation site. Thistechnique can promote healing in acute or chronic wound and/or burns.See, e.g., Xie et al. “The clinical effectiveness of negative pressurewould therapy: a systematic review,” Journal of Wound Care (2010) Vol.19 (11): 490-495.

Accordingly, in some embodiments, the dissolvable hydrogel compositionsdescribed herein can further comprise a film for covering thedissolvable hydrogel or dissolvable hydrogel layer described herein, anda drainage tube connected to an opening of the film such that blood orfluid exudate from a wound can be removed via the drainage tube in thepresence of vacuum or sub-atmospheric pressure. The film can provide asealing to tissue surrounding a wound and thus allow sub-atmosphericpressure to be applied to a local wound environment.

The vacuum or sub-atmospheric pressure can be applied to a wound, burnarea, or operation site continuously or intermittently, depending on thetype of wound or burn being treated. The vacuum or sub-atmosphericpressure can be created using any art-recognized device or apparatus,including, e.g., wall suction apparatus, surgical vacuum bottles, and/orany commercial systems designed for vacuum assisted closure. In someembodiments, such device or apparatus can provide controlled levels ofcontinuous or intermittent sub-atmospheric pressure ranging from about25 mmHg to about 400 mmHg or from about 25 mmHg to 200 mmHg.

In some embodiments, the vacuum device or apparatus can comprise avacuum generator and optionally a container to collect blood or fluidexudate from a wound. The vacuum device or apparatus can be designed tosuit the needs of different situations (e.g., but not limited tohospital setting, home use, and/or during transportation in anambulance).

Applications of the Dissolvable Hydrogels and/or Dissolvable HydrogelCompositions Described Herein and Methods of Uses

The dissolvable hydrogels, dissolvable hydrogel compositions, and/orkits described herein can be used in any biomedical applications whereadherence of the hydrogels to a surface (e.g., a tissue surface, a woundsurface, and/or a non-biological surface) followed by a subsequentrelease of the hydrogel from the surface is desirable. Where the surfaceis a delicate surface, e.g., a tissue surface or a wound surface,release or removal of an adhesive hydrogel from the surface by aphysical force, e.g., mechanical debridement and/or surgical incisioncan be undesirable, as it can potentially create undesirable damageand/or trauma to the surface. In accordance with embodiments of variousaspects described herein, the dissolvable hydrogel described herein,while adhesive to a tissue surface, can be dissolved by addition of athiolate compound, thus releasing the dissolvable hydrogel off thesurface and allowing the surface to be re-exposed. Exemplaryapplications that can be benefited from the reversibility of thedissolvable hydrogel or dissolvable hydrogel composition include, butare not limited to, wound management, tissue and/or organrepair/regeneration, temporary cell scaffolding, drug delivery, and/orany combinations thereof.

As used herein, the phrase “reversibility of the dissolvable hydrogel”refers to ability of converting the dissolvable hydrogel describedherein to a solution or any flowable state by addition of a nucleophile,e.g., a thiolate compound. Without wishing to be bound by theory,conversion of the dissolvable hydrogel described herein to a flowablestate or a solution is based on thioester-thiol exchange reaction.However, the flowable state or the solution docs not necessarily need tobe able to re-form a hydrogel. For example, the thioester-thiol exchangereaction can prevent hydrogel re-formation after dissolving the hydrogelto solution.

In some embodiments, the dissolvable hydrogels, dissolvable hydrogelcompositions, and/or kits described herein can be used to improve woundmanagement where existing dressings and/or sealants applied on a woundare removed by physical force such as mechanical debridement and/orsurgical incision. Accordingly, methods for wound management in asubject are also provided herein. In one aspect, the method comprises(a) contacting a wound in a subject with a hydrogel compositioncomprising a dissolvable hydrogel layer, wherein the dissolvablehydrogel layer comprises first linear, branched, and/or dendriticcrosslinkable polymers and second linear, branched, and/or dendriticcrosslinkable polymers covalently held together, wherein the firstcrosslinkable polymers and/or the second crosslinkable polymers compriseat least one thioester linkage or functional group in their molecularstructures; and (b) allowing the dissolvable hydrogel layer to adhere totissue surrounding the wound. In some embodiments, the method furthercomprises dissolving the dissolvable hydrogel layer by adding anucleophile, thereby releasing the hydrogel layer from the wound. In oneembodiment, the nucleophile can comprise a thiolate compound ormolecule. In these embodiments, at least some of the thioester linkagespresent within a dissolvable hydrogel network can be contributed fromone or both of the first crosslinkable polymers and the secondcrosslinkable polymers that comprise a thioester linkage or functionalgroup in their molecular structure. In these embodiments, the firstcrosslinkable polymers and/or the second crosslinkable polymers can becovalently linked together via any art-recognized chemical reactions,including, e.g., but not limited to an amine-ester reaction.

In another aspect, the method comprises (a) contacting a wound in asubject with a hydrogel composition comprising a dissolvable hydrogellayer, wherein the dissolvable hydrogel layer comprises linear,branched, and/or dendritic crosslinkable polymers held together bythioester linkages formed between the first crosslinkable polymer andthe second crosslinkable polymer; and (b) allowing the dissolvablehydrogel layer to adhere to tissue surrounding the wound. In someembodiments, the method further comprises dissolving the dissolvablehydrogel layer by adding a nucleophile, thereby releasing the hydrogellayer from the wound. In one embodiment, the nucleophile can comprise athiolate compound or molecule. In some embodiments, the firstcrosslinkable polymers and the second crosslinkable polymers do notnecessarily possess thioester linkage or functional group in theirmolecular structures. In these embodiments, thioester linkages presentwithin a dissolvable hydrogel can result or be formed from covalentinteraction between the first crosslinkable polymers and the secondcrosslinkable polymers. For example, the thioester linkages presentwithin a dissolvable hydrogel can result from reacting a firstcrosslinkable polymer comprising at least two thiols with a secondcrosslinkable polymer comprising crosslinking moieties (e.g., but notlimited to N-succinimidyl moiety and/or activated ester groups), whereinneither of the crosslinkable polymers has any thioester bonds in theirmolecular structure.

Without wishing to be bound by theory, a thioester-thiol exchangebetween thioester linkages in the dissolvable hydrogel layer and thiolsin the thiolate compound leads to dissolution of the dissolvablehydrogel layer. In some embodiments, the thiol-thioester exchange canalso result in formation of an amide linkage, thereby preventingre-formation of the first dissolvable hydrogel.

In some embodiments, the hydrogel composition comprising the dissolvablehydrogel layer can be pre-formed prior to contacting the wound. Upon thecontact, the dissolvable hydrogel layer can adhere to the tissuesurrounding the wound.

In alternative embodiments, the dissolvable hydrogel layer can form insitu between other components (e.g., a sheet support member, aprotectant layer, a mesh) of a hydrogel composition described herein andthe wound, and adhere to the tissue surrounding the wound, thusattaching the other components of the hydrogel composition to the wound.In these embodiments, the method can further comprise forming adissolvable hydrogel layer between other components of a hydrogelcomposition described herein and the wound by contacting the wound andthe other components of the hydrogel composition with a solution or aspray comprising a first water-soluble crosslinkable polymer and asecond water-soluble crosslinkable polymer, wherein the first and thesecond crosslinkable polymers become covalently held together to form athioester hydrogel.

In some embodiments, the first crosslinkable polymers and/or the secondcrosslinkable polymers can comprise at least one thioester linkage orfunctional group in their molecular structures.

In some embodiments, the first crosslinkable polymers and the secondcrosslinkable polymers become held together by thioester linkages formedbetween the first crosslinkable polymer and the second crosslinkablepolymer. In these embodiments, the first crosslinkable polymers and thesecond crosslinkable polymers do not necessarily possess thioesterlinkage or functional group in their molecular structures. In theseembodiments, thioester linkages present within a dissolvable hydrogelcan result or be formed from covalent interaction between thenucleophilic moieties of the first crosslinkable polymers and thecrosslinking moieties of the second crosslinkable polymers. For example,the thioester linkages present within a dissolvable hydrogel can resultfrom reacting a first crosslinkable polymer comprising at least twothiols with a second crosslinkable polymer comprising crosslinkingmoieties (e.g., but not limited to N-succinimidyl moiety and/oractivated ester groups).

In various aspects described herein, the dissolvable hydrogel layerdescribed herein can form and adhere to the tissue surrounding the woundwithin seconds to minutes, e.g., within about one second to 60 minutes,within about one second to about 30 minutes, within about one second toabout 15 minutes, within about one second to about 10 minutes, or withinabout one second to about five minutes.

While not necessary, in some embodiments, the hydrogel composition canfurther comprise a degradable or non-degradable mesh, as discussedearlier, to be used in combination with the dissolvable hydrogel toprovide additional adhesion to a tissue site. Further, the combinationof the mesh and the dissolvable hydrogel layer can provide for improvedstrength, which can be desirable when the area of tissue repair islarge, such as a tissue plane or a hernie repair.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel layer described herein canbe used, for example as a sealant, along with suture or staples tofurther close or secure a wound. When used in this manner, the sealantcan provide a leak tight barrier for liquids or air.

The dissolvable hydrogel layer of the hydrogel composition can bedissolved at any appropriate time (e.g., determined by a skilledpractitioner such as a physician or surgeon) after it is adhered to thetissue surrounding the wound. By way of example only, in someembodiments, the wound can be contacted with the hydrogel composition,e.g., to stop the bleeding, and/or provide temporary treatment of thewound, where immediate medical attention is not easily accessible suchas in a military field, in the wild, in a rural area, at home, and/orduring transportation. In these embodiments, the dissolvable hydrogellayer can be remained on the wound until the subject gains access tomore definitive medical care and/or treatment, e.g., in a clinic orhospital. Then, the medical practitioner can dissolve the dissolvablehydrogel layer by addition of a thiolate compound, thereby releasing thehydrogel composition from the wound, for example, for examination and/ortreatment. Accordingly, in some embodiments, the method can furthercomprise subjecting the re-exposed wound, upon release of the hydrogelcomposition from the wound, to a treatment and/or examination.

In another example where the hydrogel composition comprises a bioactiveagent for treatment of a wound, the dissolvable hydrogel layer can bedissolved whenever replenishment of the bioactive agent in the hydrogelcomposition or administration of a different bioactive agent isrequired. Accordingly, in some embodiments, the method can furthercomprise contacting the exposed wound, upon release or removal of theprior hydrogel composition from the wound, to another hydrogelcomposition comprising the same bioactive agent or a different bioactiveagent.

In other embodiments, the dissolvable hydrogel layer can be remained onthe wound until the wound stops bleeding and/or is completely healedbefore the dissolvable hydrogel layer is dissolved.

Accordingly, the time duration between the step of contacting the woundwith a hydrogel composition and the step of dissolving the dissolvablehydrogel layer to release the hydrogel composition from the wound canvary, for example, from about 30 minutes to about weeks or months. Insome embodiments, the time duration can vary from about one hour toabout one month, from about three hours to about two weeks, from aboutsix hours to about one week, from about 12 hours to about four days, orfrom about 24 hours to about three days

As used herein, the term “dissolving” refers to converting thedissolvable hydrogel layer to a liquid state, a solution or any flowablestate. The term “flowable state” as used herein refers to a state of amaterial having a consistency or viscosity that permits the material toflow, e.g., with the aid of a gentle wash or rinse. In some embodiments,the dissolvable hydrogel layer is dissolved by addition of a thiolatecompound to form a solution.

In some embodiments of various aspects described herein, the dissolvablehydrogels (or the dissolvable hydrogel layers) as described herein canbe used with vacuum assisted closure as described earlier. For example,a dissolvable hydrogel (or dissolvable hydrogel layer) described hereincan be applied to a wound, where the dissolvable hydrogel (ordissolvable hydrogel layer) can then be covered with a film to which avacuum hose is connected. Accordingly, in some embodiments of variousaspects described herein, the method can further comprise applyingvacuum or providing a sub-atmospheric pressure to the wound, after thedissolvable hydrogel layer has adhered to the tissue surrounding thewound. In some embodiments, the method can further comprise, prior toapplication of vacuum to the wound, covering the dissolvable hydrogel(or dissolvable hydrogel layer) with a film or a thin material, to whicha drainage tube is connected. The film can provide a sealing to tissuesurrounding a wound and thus allow sub-atmospheric pressure to beapplied to a local wound environment.

The vacuum or sub-atmospheric pressure can be applied to a wound, burnarea, or operation site continuously or intermittently, depending on thetype of wound or burn being treated. The vacuum or sub-atmosphericpressure can be created using any art-recognized device or apparatus,including, e.g., wall suction apparatus, surgical vacuum bottles, and/orany commercial systems designed for vacuum assisted closure. In someembodiments, such device or apparatus can provide controlled levels ofcontinuous or intermittent sub-atmospheric pressure ranging from about25 mmHg to about 400 mmHg or from about 25 mmHg to 200 mmHg.

When it is desired to remove the dissolvable hydrogel composition fromthe wound (e.g, when it is time to change the wound dressing or bandage,or for examination and/or treatment), the vacuum or sub-atmosphericpressure applied to the wound can be turned off. A nucleophile describedherein (e.g., a thiolate compound or molecule) can be applied to thedissolvable hydrogel (e.g., by injection) to dissolve the hydrogel,which can then be removed from the wound using vacuum. The film or thinmaterial, if present, can be also removed. Alternatively, the film orthin material can be removed prior to adding a nucleophile (e.g., athiolate compound or molecule) to the dissolvable hydrogel adhered tothe wound and subsequent removal of the dissolved hydrogel with avacuum. Accordingly, in some embodiments of various aspects describedherein, the method can further comprise, upon dissolving the dissolvablehydrogel or hydrogel layer, removing at least the dissolved hydrogelfrom the wound with vacuum. In some embodiments, blood, fluid exudate,and/or particulates present on the wound surface can also be removed byvacuum during removal of the dissolved hydrogel. In some embodiments,the vacuum assisted closure can be repeated.

A Thiolate Compound or Molecule:

A thiolate compound or molecule for use to dissolve the dissolvablehydrogel layer can be a compound or molecule comprising a thiol group(—SH). In some embodiments, the thiolate compound is a small molecule,e.g., less than 1 kDa, less than 500 Da, less than 400 Da, less than 300Da, less than 200 Da, less than 100 Da or lower. In some embodiments, athiolate compound is a water-soluble macromolecule greater than 500 Da.Examples of thiolate compounds include, without limitations, linear,branched and/or dendritic multi-thiol macromolecules,poly(ethyleneglycol) thiol, thiol-containing glycerol, thiol-containingpolyglycerol, thiol-containing polypeptides, cysteine, cystine, alkylester of cysteine, alkyl ester of cystine, MeSCH2SH,(R)/(S)-3-methyl-3-sulfanylhexan-1-ol, Ethanethiol, 1-Propanethiol,2-Propanethiol, Butanethiol, tert-Butyl mercaptan, Pentanethiols,Thiophenol, Dimercaptosuccinic acid, Thioacetic acid,5-mercapto-4H-[1,2,4]triazol-3-ol, 2-mercaptoacetamide,2-Mercaptoethanol, 1,2-Ethanedithiol, Ammonium thioglycolate,Cysteamine, Methyl thioglycolate, Thiolactic acid,1-Mercapto-2-propanol, 2-methoxyethanethiol, 3-Mercapto-1-propanol,2,3-Dimercapto-1-propanol, 1-Thioglycerol, Mercaptosuccinic acid,4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol, N-Carbamoyl-L-cysteine,2-Methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid,N-Acetylcysteamine, 3-Methyl-1-butanethiol, 1,5-Pentanedithiol,4-Chlorothiophenol, 4-Aminothiophenol, Benzyl mercaptan,2-furanmethanethiol, 3-mercaptohexanol, furfuryl thiol, derivativesthereof, a disulfide complex of one or more of the aforementionedcompounds, and any combinations thereof. In some embodiments, thethiolate compound is selected such that it is inert and does not reactwith the tissue, or cause any adverse or undesirable effect to thetissue. In some embodiments, the thiolate compound also encompasses amixture of thiolate compounds described herein.

The thiolate compound can be formulated in any form to suit theapplication format, e.g., but not limited to spraying and/or injectionand/or bath. In some embodiments, the thiolate compound can beformulated as a solution, a spray, powder, or any combinations thereof.In one embodiment, the thiolate compound is provided in an aqueousbuffered solution. When the thiolate compound is applied to thedissolvable hydrogel layer adhered to a biological tissue, the pH of theaqueous buffered solution is desired to be maintained at a physiologicalpH, e.g., between pH ˜6 and pH ˜8.

Without wishing to be bound by theory, addition of the thiolate compoundto the dissolvable hydrogel layer results in a thioester-thiol exchange(or used interchangeably herein with the term “thiol-thioesterexchange”). Thiol-thioester exchange in water, where a thiol replaces athiol in a thioester, is known to occur readily in solution with smallmolecules. For example, adding an equivalent number of free thiols to asolution of thioester small molecules (e.g., thiol: thioesterstoichiometric ratio is about 1:1) is sufficient to lead tothiol-thioester exchange. However, thiol-thioester exchange inmacromolecule assemblies, e.g., hydrogel systems, has not been explored.Surprisingly, thioester crosslinked hydrogels (also termed “dissolvablehydrogels” described herein” are shown to be unexpectedly stable. Asshown in FIG. 7, when the equivalent number of thiols added to athioester hydrogel was four (based on the number thioester linkages),there was almost no change in mechanical properties over a period of atleast about 60 minutes. Thiol-thioester exchange reactions appeared tooccur very slowly or insignificantly. That is, adding an equivalentnumber of free thiols to a thioester crosslinked hydrogel is notsufficient to allow significant thiol-thioester exchange to occur.Instead, the thioester crosslinked hydrogel is dissolved upon additionof an excess of free thiols (e.g., as shown in FIG. 4). These combineddata indicate that the thioester exchange reaction in a thioestercrosslinked hydrogel is generally slow and unfavorable unless an excessof free thiols is used. Without wishing to be bound by theory, as thepolymer chains are generally confined to an area via the crosslinkedhydrogel, a conformational change or rearrangement of polymer chains canbecome less favorable.

Further, as shown in FIG. 4, the rate of hydrogel dissolution canincrease with concentration of the thiolate compound and/or the pH ofthe media in which the thiolate compound is dispersed.

Accordingly, the concentration of the thiolate compound added can, inpart, depend on the number of thioester linkages present in thedissolvable hydrogel layer, pH of the media in which the thiolatecompound is dispersed, and/or a desirable rate of hydrogel dissolution.To provide excess thiols relative to available thioester linkages, thestoichiometric ratio (e.g., mole ratio) of the total thiol groups addedto the total thioester linkages present in the dissolvable hydrogeldescribed herein should be greater than 1:1, greater than 2:1; greaterthan 3:1, greater than 4:1, greater than 5:1, greater than 10:1, greaterthan 20:1, greater than 25:1, greater than 50:1 or higher. In someembodiments, the thiolate compound is provided as a saturated solution.The term “saturated solution” as used herein refers to a solution of thethiolate compound present in an amount that reaches the point at whichno more of the thiolate compound can be dissolved in the solution andany additional amounts will appear as a separate phase. The method neednot be limited to a fully saturated thiolate solution but can include asubstantially saturated or near saturated thiolate solution orconcentrated thiolate solution.

As used herein, the term “wound” refers to physical disruption of thecontinuity or integrity of tissue structure caused by a physical (e.g.,mechanical) force, a biological (e.g., thermic or actinic force), or achemical means. In one embodiment, the term “wound” encompasses woundsof the skin. The term “wound” also encompasses contused wounds, as wellas incised, stab, lacerated, open, penetrating, puncture, abrasions,grazes, burns, frostbites, corrosions, wounds caused by ripping,scratching, pressure, burns, and biting, and other types of wounds. Insome embodiments, the term “wound” encompasses ulcerations (e.g.,ulcers), or ulcers of the skin. In some embodiments, the term “wound”also includes surgical wounds.

The wound can be acute or chronic. As used herein, the term “chronicwound” refers to a wound that does not fully heal even after a prolongedperiod of time (e.g., two to three months or longer). Chronic wounds,including pressure sores, venous leg ulcers and diabetic foot ulcers,can simply be described as wounds that fail to heal. Whilst the exactmolecular pathogenesis of chronic wounds is not fully understood, it isacknowledged to be multi-factorial. As the normal responses of residentand migratory cells during acute injury become impaired, these woundsare characterized by a prolonged inflammatory response, defective woundextracellular matrix (ECM) remodeling and a failure ofre-epithelialization.

The wound can be an internal wound, e.g. where the external structuralintegrity of the skin is maintained, such as in bruising or internalulceration, or external wounds, particularly cutaneous wounds, andconsequently the tissue can be any internal or external bodily tissue.In some embodiment the tissue is skin (such as human skin), i.e. thewound is a cutaneous wound, such as a dermal or epidermal wound.

Wounds can be classified in one of two general categories, partialthickness wounds or full thickness wounds. A partial thickness wound islimited to the epidermis and superficial dermis with no damage to thedermal blood vessels. A full thickness wound involves disruption of thedermis and extends to deeper tissue layers, involving disruption of thedermal blood vessels. The healing of the partial thickness wound occursby simple regeneration of epithelial tissue. Wound healing in fullthickness wounds is more complex.

In some embodiments, the wound is selected from the group consisting ofcuts and lacerations, surgical incisions or wounds, punctures, grazes,scratches, compression wounds, abrasions, friction wounds (e.g. nappyrash, friction blisters), decubitus ulcers (e.g. pressure or bed sores),thermal effect wounds (burns from cold and heat sources, either directlyor through conduction, convection, or radiation, and electricalsources), chemical wounds (e.g. acid or alkali burns) or pathogenicinfections (e.g. viral, bacterial or fungal) including open or intactboils, skin eruptions, blemishes and acne, ulcers, chronic wounds,(including diabetic-associated wounds such as lower leg and foot ulcers,venous leg ulcers and pressure sores), skin graft/transplant donor andrecipient sites, immune response conditions, e.g. psoriasis and eczema,stomach or intestinal ulcers, oral wounds, including a ulcers of themouth, damaged cartilage or bone, amputation wounds, corneal lesions,and any combinations thereof.

Adhesion formation is a major post-surgical complication. The incidenceof clinically significant adhesion is about 5 to 10 percent with somecases as high as 100 percent. Among the most common complications ofadhesion formation are obstruction, infertility, and pain. Occasionally,adhesion formation requires a second operative procedure to removeadhesion, further complicating the treatment. Given the wide-spreadoccurrence of post-surgical adhesions, a number of approaches have beenattempted for preventing adhesions (Stangel et al., “Formation andPrevention of Postoperative Abdominal Adhesions”, The Journal ofReproductive Medicine, Vol. 29, No. 3, March 1984 (pp. 143-156), anddiZerega, “The Cause and Prevention of Postsurgical Adhesions”,published by Pregnancy Research Branch, National Institute of ChildHealth and Human Development, National Institutes of Health, Building18, Room 101, Bethesda, Md. 20205.)

Exemplary approaches for prevention of post-surgical adhesion include 1)systemic administration of ibuprofen (e.g., see Singer, U.S. Pat. No.4,346,108), 2) parenteral administration of antihistamines,corticosteroids, and antibiotics, 3) intraperitoneal administration ofdextran solution and of polyvinylpyrrolidone solution, 4) systemicadministration of oxyphenbutazone, a non-steroidal anti-inflammatorydrug that acts by inhibiting prostaglandin production, and 5)administration of linear synthetic and natural polymers (Hubell 6060582;Fertil. Steril., 49:1066; Steinleitner et al. (1991) “Poloxamer 407 asan Intraperitoneal Barrier Material for the Prevention of PostsurgicalAdhesion Formation and Reformation in Rodent Models for ReproductiveSurgery,” Obstetrics and Gynecology, 77(1):48 and Leach et al. (1990)“Reduction of postoperative adhesions in the rat uterine horn model withpoloxamer 407”, Am. J. Obstet. Gynecol., 162(5):1317. Linsky et al.,1987 “Adhesion reduction in a rabbit uterine horn model using TC-7,” J.Reprod. Med., 32:17, Diamond et al., 1987 “Pathogenesis of adhesionsformation/reformation: applications to reproductive surgery,”Microsurgery, 8:103).

For example, formation of post-surgical adhesions involving organs ofthe peritoneal cavity and the peritoneal wall is undesirable result ofabdominal surgery. This occurs frequently and arises from surgicaltrauma. During the operation, serosanguinous (proteinaceous) exudate isreleased which tends to collect in the pelvic cavity (Holtz, G., 1984).If the exudate is not absorbed or lysed within a short period of time,it becomes ingrown with fibroblasts, with subsequent collagen depositionoccurs leading to adhesions.

In some embodiments, the method described herein can be used to preventformation of adhesions between injured tissues by introducing a barriercomprising the dissolvable hydrogel and/or the hydrogel compositioncomprising a dissolvable hydrogel layer described herein between theinjured tissues. This polymeric barrier can as a sheet or coating on theexposed injured tissue to prevent surgical adhesions (Urry et al., Mat.Res. Soc. Symp. Proc., 292, 253-64 (1993)). This polymeric barrier canbe controllably dissolved over a time course by addition of anappropriate amount of a thiolate compound that allows for normal healingto occur without formation of adhesions/scars etc.

In some embodiments, the wound to be contacted and/or treated by thehydrogel composition comprising a dissolvable hydrogel layer describedherein can include skin lacerations. Skin lacerations are tears in theskin produced by accidents, trauma, or as a result of a surgicalprocedure. Lacerations often require treatment in order to close thehole in the skin, stop bleeding, and/or prevent infection. Depending ondegree of lacerations, different formats of the dissolvable hydrogelcompositions (e.g., bandage, glue, sealant, and/or coating) can be usedto treat skin lacerations. For example, minor lacerations in the skincan be treated using an adhesive hydrogel bandage to cover the wound.However, larger lacerations may require a dissolvable hydrogel glue tohelp seal the wound. For example, a dissolvable hydrogel composition ina form of glue can be used to treat lacerations deeper than 0.25 incheshaving a jagged edge or loose flap of tissue. The location of thelaceration can also affect the form of treatment. For example, it can bemore desirable to treat a skin laceration on a joint using glue becauseadhesive bandage can tend to limit mobility of the joint. The use ofglues to treat skin lacerations can also reduce the chance of scarformation.

In some embodiments, the wound to be contacted and/or treated by thehydrogel composition comprising a dissolvable hydrogel layer describedherein can include liver lacerations. Lacerations of the liver can occurfrom trauma or as a result of a surgical procedure. The liver is ahighly vascularized organ and bleeds profusely when lacerated ortraumatized. Liver lacerations are generally difficult to repair owingto the nature of liver tissue. Liver tissue has very weak cohesivestrength, and, consequently, sutures and staples are not satisfactorybecause they may pull through the liver tissue. The lack of satisfactorywound treatment methods for liver lacerations combined with the factthat it is difficult to reach the veins that feed the liver rendersliver lacerations particularly serious. In fact, severe lacerations ofthe liver often result in the patient's death due to bleeding.

In some embodiments, the hydrogel composition (e.g., in a form of asealant) comprising a dissolvable hydrogel described herein can be usedin lung surgery to decrease or eliminate some of the problematic aspectsof lung surgery, such as treatment of pneumothorax and pulmonary leaks.Types of lung surgery include, without limitations, lobectomy, lungbiopsy, lung-tissue removal, pneumonectomy, thoracoscopy, andthoracotomy. Risks associated with lung surgery include wound infection,post-surgical internal bleeding, air leaks through the lung wall, painor numbness at the incision site, and inflammation of the lungs(pneumonia). Further, air leakage is frequently observed after thoracicprocedures, such as pulmonary resection and decortication. Thedissolvable hydrogel can be used as a sealant to create an air-tightseal so as to prevent or reduce severe complications, such asbronchopleural fistulas and/or infection resulting from extended chesttube drainage, extended recovery time, and/or postoperative morbidityrelated to pulmonary surgery.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused for sealing cornea perforation. Corneal perforations afflict afraction of the population and are produced by a variety of medicalconditions (e.g., but not limited to, infection, inflammation, xerosis,neurotrophication, and/or degeneration) and/or traumas (e.g., but notlimited to, chemical, thermal, surgical, and penetrating).Unfortunately, corneal perforations often lead to loss of vision and adecrease in an individual's quality of life. Depending on the type andthe origin of the perforation, different treatments are currentlyavailable from suturing the wound to a cornea graft. However, this is adifficult surgical procedure given the delicate composition of thecornea and the severity of the wound, which increase the likelihood forleakage and severe astigmatism after surgery. In some embodiments whereperforations cannot be treated by standard suture procedures, thedissolvable hydrogels described herein (e.g., in a form of tissueadhesive and/or glue) can be used to repair the wound. This type oftreatment can be simple, quick and safe, and correspond to therequirement of a quick restoration of the integrity of the globe toavoid further complications.

Besides an easy and fast application on the wound, the criteria for anadhesive are to 1) bind to the tissue (necrosed or not, very often wet)with an adequate adhesion force, 2) be non-toxic, 3) be biodegradable orresorbable, 4) be sterilizable and 5) not interfere with the healingprocess. Various alkyl-cyanoacrylates are available for the repair ofsmall perforations. However, the monomers of these “super glues”, inparticular those with short alkyl chains, can be toxic. They alsopolymerize too quickly leading to applications that might be difficultand, once polymerized, the surface of the glue is rough and hard whichcan result in patient discomfort and a need to wear contact lens. Eventhough cyanoacrylate is tolerated as a corneal sealant, a number ofcomplications have been reported including cataract formation, cornealinfiltration, glaucoma, giant papillary conjunctivitis, and symblepharonformation. Furthermore, in more than 60% of the patients, additionalSurgical intervention was needed.

Other glues have also been developed, for example, adhesive hemostats,based on fibrin, being usually constituted of fibrinogen, thrombin andfactor XIII, as well as systems with fibrinogen and photosensitizersactivated with light. However, autologous products (time consuming in anemergency) or severe treatments of the non-autologous products beforeclinical use are needed to avoid any contamination to the patient. Anideal sealant for corneal perforations should 1) not impair normalvision, 2) quickly restore the intraocular pressure, IOP, 3) maintainthe structural integrity of the eye, 4) promote healing, 5) adhere tomoist tissue surfaces, 6) possess solute diffusion properties which aremolecular weight dependent and favorable for normal cornea function, 7)possess rheological properties that allow for controlled placement ofthe polymer on the wound, and 8) polymerize under mild conditions.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused for sealing a retinal hole. Existing techniques used for thetreatment of retinal holes such as cryotherapy, diathermy andphotocoagulation are unsuccessful in the case of complicated retinaldetachment, partly because of the delay in the application and/or theweak strength of the chorioretinal adhesion. Cyanoacrylate retinopexy ispreviously discussed for use in special cases and shown that thechorioretinal adhesion can be stronger and last longer than the earliertechniques. As noted previously with regard to corneal perforationtreatment, the extremely rapid polymerization of cyanoacrylate glues(for example, risk of adhesion of the injector to the retina), thedifficulty to use them in aqueous conditions and the toxicity are someof the inconvenience and/or risks associated with the method of usingcyanoacrylate glues. While the polymerization can be slowed down byadding iophendylate to the monomers, the reaction still occurs in two tothree seconds. Risks of retinal tear at the edge of the treated hole canalso be observed because of the hardness of cyanoacrylate oncepolymerized.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused for sealing a corneal transplant. In a corneal transplant thesurgeon usually makes approximately 16 sutures around the transplant tosecure the new cornea in place. A sutureless procedure by using thedissolvable hydrogel and/or the hydrogel composition comprising adissolvable hydrogel described herein can be desirable, as 1) suturescan provide a site for infection, 2) the sutured cornea can take threemonths to heal before the sutures need to be removed, and/or 3) thestrain applied to the new cornea tissue from the sutures can distort thecornea.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused in oculoplastics or oculoplastic surgery. For example,blepharoplasty incisions blepharoplasty is an operation to remove excessskin, fat and muscle from around the eyes to correct droopy eyelids andbagginess under the eyes. It can be performed on the upper lids andlower lids, at the same time or separately. The operation may be doneusing either conventional or laser techniques. For surgery on the uppereyelids, cuts are made into the natural lines and creases in the lid,and into the laughter lines at the corner of the eye. For surgery on thelower eyelids, a cut is usually made just below the eyelashes. Thismeans the scars lull along the eye's natural folds, concealing them asmuch as possible. Excess fat, muscle and loose skin are removed, and thecut is currently closed using sutures. If only fat is being removed,sometimes the cut is made on the inside of the lower eyelid, leaving novisible scar. A dissolvable hydrogel described herein formulated as atissue adhesive can provide a means to secure the cuts made duringsurgery.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused as sealants using the methods described herein in gastrointestinalanastomosis procedures. Gastrointestinal anastomosis is the technique ofjoining two pieces of bowel together. There are many techniques forgastro-intestinal anastomosis, including both mechanical stapledtechniques and hand-sutured procedures. The technique may involve asimple end-end anastomosis of two pieces of jejunum, a more complexcolo-anal anastomosis, or a biliary enteric join. One of the problemswith techniques employing sutures or staples is that leakage may occuraround the sutures or staples. See, for example, Bruce et al. Br. J.Surg. 88:1157-1168 (2001) reporting leakage rates of 5-8%. Accordingly,the dissolvable hydrogel as sealants and methods of use described hereincan be used to supplement the sutures or staples used in intestinalanastomoses, providing a better seal that can reduce leakage. Theconsequences of a failed anastomosis are severe and frequentlylife-threatening. Although failures can be caused by myriad factors,including poor surgical technique (e.g., sutures that were not insertedcorrectly, knots that were tied too tightly rendering the endsischaemic, and/or incorrect use of a staple gun), in some embodiments,use of the dissolvable hydrogel as sealants and/or methods of usedescribed herein can decrease or eliminate some of the causes of failedgastrointestinal anastomosis procedures.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused as sealants using the methods described herein in prostatectomyurethral-bladder anastomosis procedures. Prostatectomy urethral-bladderanastomosis is the technique of joining together a patient's ureter andbladder after surgical removal of his prostate gland. Failures can becaused by myriad factors, including poor surgical technique (e.g.,sutures that were not inserted correctly; and/or knots that were tiedtoo tightly rendering the ends ischaemic). In some embodiments, use ofthe dissolvable hydrogel as sealants and/or methods of use describedherein can decrease or eliminate some of the causes of failedprostatectomy urethral-bladder anastomosis procedures.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused as sealants and/or tissue scaffold in the methods described hereinto repair cartilage, meniscus and/or disk. Cartilaginous tissues playimportant roles in contributing to load support and energy dissipationin the joints of the musculoskeletal system. These tissues includearticular cartilage, which is predominantly an avascular, and alympharictissue with very low cell-density. As a result, articular cartilage haslimited capacity for self-repair following injury or aging. Degenerationof cartilage in the meniscus, intervertebral disks, or joints can leadto severe and debilitating pain in patients. Injuries to these tissuesare often retained for many years and may eventually lead to more severesecondary damage. See Moskowitz, R. W., Osteoarthritis: diagnosis andmedical/surgical management. 2nd ed.; W.B. Saunders Company: 1984.Today, more than one million knee, hip, and shoulder joint surgicalprocedures are performed annually in the United States as a consequenceof trauma or a lifetime of wear and tear. See Praemer, A.; Furner, S.;Rice, D. P. Musculoskeletal Conditions in the United States, AmericanAcademy of Orthopedic Surgeons: Rosemont, Ill., 1999. Despite the largenumber of patients suffering from cartilage degeneration, the onlyexisting treatment options for cartilage degeneration include chronicadministration of anti-inflammatory agents, total joint replacement,osteotomy, and/or allograft transplantation, each of which leads tomixed long-term results.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused as sealants and/or glues using the methods described herein intissue plane applications. For example, the dissolvable hydrogel and/orthe hydrogel composition comprising a dissolvable hydrogel describedherein can be applied between two planes of tissue to seal themtogether. Over time the dissolvable hydrogel can be controllablydissolved by addition of a thiolate compound as new tissue grows intothe area. Example applications include, but are not limited to, a numberof cosmetic and tissue restoration surgeries. In some embodiments, thedissolvable hydrogel and/or the hydrogel composition comprising adissolvable hydrogel described herein can be used when the proceduresinvolve significant tissue plane separation that may result in formationof seroma with associated complications, such as infection, e.g.,general surgery procedures, such as mastectomies and lumpectomies,and/or plastic surgery procedures, such as abdominoplastys, rhytidectomyor rhinoplastys, mammaplasty and reconstruction, forehead lifts andbuttocks lifts, as well as skin grafts, biopsy closure, cleft-palatereconstruction, hernia repair, lymph node resection, groin repair,Caesarean section, laparoscopic trocar repair, vaginal tear repair, andhand surgery.

Adhesion formation is a major post-surgical complication. The incidenceof clinically significant adhesion is about 5 to 10 percent with somecases as high as 100 percent. Among the most common complications ofadhesion formation are obstruction, infertility, and pain. Occasionally,adhesion formation requires a second operative procedure to removeadhesion, further complicating the treatment. Given the wide-spreadoccurrence of post-surgical adhesions, a number of approaches have beenattempted for preventing adhesions (Stangel et al., “Formation andPrevention of Postoperative Abdominal Adhesions”, The Journal ofReproductive Medicine, Vol. 29, No. 3, March 1984 (pp. 143-156), anddiZerega, “The Cause and Prevention of Postsurgical Adhesions”,published by Pregnancy Research Branch, National Institute of ChildHealth and Human Development, National Institutes of Health, Building18, Room 101, Bethesda, Md. 20205.)

Exemplary approaches for prevention of post-surgical adhesion include 1)systemic administration of ibuprofen (e.g., see Singer, U.S. Pat. No.4,346,108), 2) parenteral administration of antihistamines,corticosteroids, and antibiotics, 3) intraperitoneal administration ofdextran solution and of polyvinylpyrrolidone solution, 4) systemicadministration of oxyphenbutazone, a non-steroidal anti-inflammatorydrug that acts by inhibiting prostaglandin production, and 5)administration of linear synthetic and natural polymers (Hubell 6060582;Fertil. Steril., 49:1066; Steinleitner et al. (1991) “Poloxamer 407 asan Intraperitoneal Barrier Material for the Prevention of PostsurgicalAdhesion Formation and Reformation in Rodent Models for ReproductiveSurgery,” Obstetrics and Gynecology, 77(1):48 and Leach et al. (1990)“Reduction of postoperative adhesions in the rat uterine horn model withpoloxamer 407”, Am. J. Obstet. Gynecol., 162(5):1317. Linsky et al.,1987 “Adhesion reduction in a rabbit uterine horn model using TC-7,” J.Reprod. Med., 32:17, Diamond et al., 1987 “Pathogenesis of adhesionsformation/reformation: applications to reproductive surgery,”Microsurgery, 8:103).

For example, formation of post-surgical adhesions involving organs ofthe peritoneal cavity and the peritoneal wall is undesirable result ofabdominal surgery. This occurs frequently and arises from surgicaltrauma. During the operation, serosanguinous (proteinaceous) exudate isreleased which tends to collect in the pelvic cavity (Holtz, G., 1984).If the exudate is not absorbed or lysed within a short period of time,it becomes ingrown with fibroblasts, with subsequent collagen depositionoccurs leading to adhesions.

In some embodiments, the method described herein can be used to preventformation of adhesions between injured tissues by introducing a barriercomprising the dissolvable hydrogel and/or the hydrogel compositioncomprising a dissolvable hydrogel layer described herein between theinjured tissues. This polymeric barrier can as a sheet or coating on theexposed injured tissue to prevent surgical adhesions, and can becontrollably dissolved over a time course by gradual addition of anappropriate amount of a thiolate compound that allows for normal healingto occur without formation of adhesions/scars etc.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused as sealants and/or glues using the methods described herein torepair, close and/or secure vascular and/or cardiovascular tissue.Representative procedures include, for example, coronary artery bypassgrafts, coronary angioplasty, diagnostic cardia catheterization, carotidendarterectomy, and valve repair. An additional use of the dissolvablehydrogel and/or the hydrogel composition comprising a dissolvablehydrogel described herein as sealants can include repair of cardiactissue after a myocardial infarction. The dissolvable hydrogel and/orthe hydrogel composition comprising the dissolvable hydrogel describedherein can be applied to the infarcted tissue to provide structuralsupport to the weakened tissue. For example, the dissolvable hydrogeldescribed herein can act as a sleeve for the cardiac tissue.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused as adhesive, coating, sealants and/or glues using the methodsdescribed herein to repair a dura tissue. Dura tissue is a fibrousmembrane covering the brain and the spinal cord and lining the innersurface of the skull. Existing methods of dural repair involve theapplication of interrupted sutures and the use of dural replacementmaterials (duraplasty), which is a meticulous surgery and suffers fromthe limitation that pinholes produced by surgical needles can causeleakage. Moreover, intraoperative dehydration can shrink the duracreating a difficult closure since it is difficult to approximate theedges with sutures. In older patients, the dura can be often moresusceptible to tearing when stretched and/or sutured because the duracan be thin and fragile. Adhesives such as fibrin have been used forrepair of dura tissue, but have had limited success. See “Glue in theRepair of Dural Defects in Craniofacial Resections,” J. Latyngology andOtology 106: 356-57 (1992); Kjaergard et al., “Autologous Fibrin GluePreparation and Clinical Use in Thoracic Surgery,” Eur. J. Cardio-Thorc.Surg. 6: 52-54 (1992); Thompson et al., “Fibrin Glue: A Review of ItsPreparation, Efficacy, and Adverse Effects as a Topical Hemostat,” DrugIntelligence and Clinical Pharmacy 22: 946-52 (1988); and Brennan,“Fibrin Glue,” Blood Reviews 5: 240-44 (1991). The dissolvable hydrogelsas sealants and methods of use described herein can be used to repairthe dura after a craniotomy or laminectomy and/or prevent postoperativeleakage of cerebrospinal fluid. See Preul et al. Neurosurgery53:1189-1199 (2003) and Balance, Calif. in Some Points in the Surgery ofthe Brain and Its Membranes. London, Macmillan & Co. Injection SiteWound.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can beused in the methods described herein to deliver a bioactive agent suchas growth factor. For example, the dissolvable hydrogel and/or thehydrogel composition comprising a dissolvable hydrogel described hereincan comprise a bioactive agent described herein and be used as a patchto cover an infracted tissue in a myocardial infarction to help reduceloss of tissue function. In some embodiments, the dissolvable hydrogeland/or the hydrogel composition comprising a dissolvable hydrogeldescribed herein can be used for vascular applications where thedissolvable hydrogel and/or the hydrogel composition described hereincan be loaded with site-specific angiogenesis factor(s), e.g., but notlimited to, vascular endothelial growth factor, platelet derived growthfactor, and/or other angiogenesis factors. The dissolvable hydrogeland/or the hydrogel composition used as a vascular graft/patch can beused to bypass, replace, and/or repair a part of thediseased/dysfunctional blood vessel. In some embodiments, thedissolvable hydrogel and/or the hydrogel composition comprising adissolvable hydrogel described herein can form an implant comprising anangiogenesis antagonist, e.g., for inhibiting undesired angiogenesis ina specific site, such as tumor, cancer, retinopathy, or the like.

Vascular endothelial growth factor is a secreted angiogenic mitogenwhose target cell specificity appears to be restricted to vascularendothelial cells. The resulting angiogenesis properties may also beinduced using platelet derived growth factor, tissue treatment factor,and the like. The phrase “vascular endothelial growth factor” refersbroadly to all members of the vascular endothelial growth factor family,which may comprise polynucleotides, polypeptides encoded by suchpolynucleotides that facilitate angiogenesis, and the like. U.S. Pat.No. 6,040,157 to Hu et al. (hereby incorporated by reference) discussesgeneral characteristics and specific properties of vascular endothelialgrowth factor and is incorporated herein by reference. Notably, VEGF hasat least four different forms of 121, 165, 189 and 206 amino acids dueto alternative splicing, which are designated as VEGF121, VEGF165,VEGF189, and VEGF206, respectively. In some embodiments, the growthfactor can be added to the dissolvable hydrogel described herein at thetime of implantation. In some embodiments, the growth factors can beintroduced into the tissue site, e.g., vascular graft, followed bytreatment with the dissolvable hydrogel and/or composition describedherein.

The dissolvable hydrogel and/or the hydrogel composition comprising adissolvable hydrogel described herein can be utilized to diagnosedisease, promote healing and/or prevent disease or disorder by targetingor concentrating a bioactive agent such as a drug to local and regionalareas.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein can alsobe used for a variety of applications including, but not limited to,production of micro- and nanoparticles. Such materials can be used torepair an injured tissue, organ, bone, or genetic defect. Other uses ofthe dissolvable hydrogel and/or composition described herein providedherein include treatment of early, late or previously treatedmalignancies, pre-treatment of malignancies or other condition as asensitizer to augment therapy of another agent such as with radiationsensitizers, avoidance of locoregional lymph node metastasis,augmentation of local wound healing and decrease in infection,manipulation of structure and abnormal scar formation, delivery ofdrugs, cytokines or steroids-into, for example, joint capsules-insulin,glucagon, or genetically missing enzymes and for the treatment ofpost-operative pain. In one embodiment, the dissolvable hydrogel and/orthe hydrogel composition comprising a dissolvable hydrogel describedherein can be used to treat cancer. For example, the dissolvablehydrogel and/or the hydrogel composition comprising a dissolvablehydrogel described herein can be used to treat various malignancies,e.g., but not limited to, lung, colon, prostate, pancreas, ovarian,sarcoma, mesothelioma, or breast cancer at all stages.

The dissolvable hydrogel and/or the hydrogel composition comprising adissolvable hydrogel described herein can be used to deliver any agentat a specific site. The agent can be in any pharmaceutically acceptableform of an agent, including pharmaceutically acceptable salts. A largenumber of pharmaceutically active agents are known in the art and areamenable for use in the pharmaceutical compositions of the dissolvablehydrogel described herein. Pharmaceutically active agent include, butare not limited to, chemotherapeutic agents, such as radiosensitizers,receptor inhibitors and agonists or other anti-neoplastic agents; immunemodulators, anti-inflammatory agents, and bioactive agents, such ascytokines, growth factors, or steroids with or without theco-incorporation of tumor or pathogen antigens to increase theanti-neoplastic response as a means of vaccine development; localanesthetic agents; antibiotics; or nucleic acids as a means of localgene therapy.

Accordingly, methods for site-specific or systemic delivery of abioactive agent are provided herein. For example, the method comprises:a) implanting at a target site in the body of a patient in need thereofa dissolvable hydrogel and/or a hydrogel composition comprising adissolvable hydrogel layer described herein, wherein a therapeuticallyeffective amount of a biologically or pharmaceutically active agent isincorporated into the dissolvable hydrogel and/or the hydrogelcomposition; b) allowing the dissolvable hydrogel layer to adhere to thetarget site; and c) dissolving the dissolvable hydrogel layer byaddition of a thiolate compound, thereby releasing the hydrogelcomposition from the target site. In some embodiments, the thiolatecompound can be added by injection, e.g., via a syringe and/or catheter,and/or by spraying, e.g., on a skin surface.

The dissolvable hydrogel and/or the hydrogel composition comprising adissolvable hydrogel described herein can also be used in cosmeticapplications using the methods described herein. In some embodiments,the dissolvable hydrogel and/or compositions (e.g., adhesives) can beused alone or in combination with a void filler, where the crosslinkablepolymers can be injected under the skin to form the dissolvable hydrogelin situ. Alternatively, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel described herein (e.g.,adhesives) can be applied as a topical cosmetic or therapeuticcomposition, used, e.g., in connection with creams, shampoos, soaps, sunscreen, lotions to moisturize the tissue, and oils, for dermatologicalpurposes, cleansing, and the like. The dissolvable hydrogel and/or thehydrogel composition comprising a dissolvable hydrogel described herein(e.g., adhesives) can also be used with agents such as rapamycin oranalogs e.g., everolimus or blolimus, which can help minimize scaringafter plastic surgery performed on the face, body, or other externalskin area.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel layer described herein canbe injected or placed in vivo as a void filling composition or used as asealant/adhesive alone or in combination with natural polymers, e.g.,but not limited to, collagen, hyaluronic acid, gelatin, heparin, fibrinand/or heparin sulfate. Voids that can be filled using the dissolvablehydrogel and/or composition described herein include, withoutlimitations, a nasal airway, or an organ of the gastro-intestinal track,for example, in order to arrest localized bleeding and/or promotehealing following trauma, injury, or surgery.

In some embodiments, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel layer described herein canbe used where the site of the wound is not easily accessible or whensutureless surgery is desired, e.g., but not limited to, incardiovascular surgery, urinary tract surgery (e.g., nephrotomy closure,urethral repair, hypospadia repair), pulmonary surgery (e.g., sealingparenchymal & bronchial leaks, bronchopleural fistula repair, persistentair leak repairs), gastrointestinal tract and stomach surgery (e.g.,parotid cutaneous fistula, tracheo-oesophageal fistula, peptic ulcerrepair), joint surgery (e.g., cartilage repair, meniscal repair), heartsurgery (e.g., cardiac ventricular rupture repair), brain surgery (e.g.,dural defect repairs), ear surgery (e.g., ear drum perforation), andpost-surgical drainage reduction (e.g., mastectomy, axillary dissection)and alveolar osteitis (“dry socket”) and related post-surgical oralindications, and post-surgical drainage reduction (mastectomy, axillarydissection).

In cardiovascular surgery, the dissolvable hydrogel and/or the hydrogelcomposition comprising a dissolvable hydrogel layer described herein canbe used as sealants, for example, for needle holes, suture lines,diffuse and nonspecific bleeding, anastomotic bleeding, friable tissuebleeding, aortic dissections, ventricular ruptures, and fistulas.

Kits

Kits, e.g., for use in the methods described herein or in anyapplications described herein are also provided. In one aspect, a kitcomprises a) at least one or a plurality of (e.g., two or more)pre-formed dissolvable hydrogel composition(s) described herein and b) athiolate compound. Thus, a user can directly apply the pre-formeddissolvable hydrogel composition to a target site (e.g., a wound).

In another aspect, a kit comprises a) at least two components of thecrosslinkable polymers to be applied to a target site (e.g., a wound) toform a dissolvable hydrogel described herein in situ at the target site,wherein the crosslinkable polymers are each at least about 200 Da orhigher (e.g., at least about 500 Da, at least about one kDa or higher),and b) a thiolate compound. In some embodiments, at least two componentsof the crosslinkable polymers can include a) a first water-solublelinear, branched, and/or dendritic crosslinkable polymer comprising atleast two thiol moieties, and b) a second water-soluble linear,branched, and/or dendritic crosslinkable polymer that can react with thefirst crosslinkable polymer to form a dissolvable and adhesive hydrogel,wherein the second crosslinkable polymer comprises at least twocrosslinking moieties that are capable of tenting with the thiolmoieties of the first crosslinkable polymer to form thioester linkagesbetween the first and the second crosslinkable polymers. In otherembodiments, at least two components of the crosslinkable polymers caninclude a) a first water-soluble linear, branched, and/or dendriticcrosslinkable polymer comprising at least two thioester moieties, and b)a second water-soluble linear, branched, and/or dendritic crosslinkablepolymer that can react with the first crosslinkable polymer to form adissolvable and adhesive thioester hydrogel, wherein the secondcrosslinkable polymer comprises at least two crosslinking moieties forcrosslinking with the first crosslinkable polymer. In other embodiments,at least two components of the crosslinkable polymers can include a) afirst water-soluble linear, branched and/or dendritic crosslinkablepolymer that can react with the second crosslinkable polymer to form adissolvable and adhesive thioester hydrogel, wherein the firstcrosslinkable polymer comprises at least two nucleophilic moieties(e.g., but not limited to, thiol, alcohol, amine) for crosslinking withthe second crosslinkable polymer, and b) a second water-soluble linear,branched and/or dendritic crosslinkable polymer comprises at least twothioester moieties. In some embodiments, the first crosslinkable polymercan comprise thioester moieties.

The first crosslinkable polymer and the second crosslinkable polymer caneach be independently formulated in a form selected from the groupconsisting of a spray, a foam, a gel, a solution, a powder, and anycombinations thereof.

In some embodiments, the kit can further comprise at least one reagent.For example, a reagent can include a reconstitution buffer if thecomponents of the crosslinkable polymers are provided as a powder.Additionally or alternatively, a reagent can include an antisepticagent, e.g., for cleaning a wound before treatment.

In some embodiments, the at least two components of the crosslinkablepolymers can be provided in a dual-barrel syringe. In these embodiments,the at least two components of the crosslinkable polymers can be mixedtogether by passing through a mixing tip, which can be releasablyattached to the outlet of the dual-barrel syringe.

In some embodiments of the kits described herein, the kit can furthercomprise a bioactive agent described herein. In some embodiments, thebioactive agent can be incorporated into the pre-formed dissolvablehydrogel described herein or in at least one component of thecrosslinkable polymers. In other embodiments, the bioactive agent can beprovided in a separate container.

In some embodiments of the kits described herein, the thiolate compoundcan be formulated in a form selected from the group consisting of aspray, a foam, a solution, a gel, a powder, and any combinationsthereof. Non-limiting examples of the thiolate compound can includelinear, branched and/or dendritic multi-thiol macromolecules,polyethylene glycol) thiol, thiol-containing glycerol, thiol-containingpeptides, cysteine, cystine, alkyl ester of cysteine, alkyl ester ofcystine, McSCH2SH, (R)/(S)-3-methyl-3-sulfanylhexan-1-ol, Ethanethiol,1-Propanethiol, 2-Propanethiol, Butanethiol, tert-Butyl mercaptan,Pentanethiols, Thiophenol, Dimercaptosuccinic acid, Thioacetic acid,5-mercapto-4H-[1,2,4]triazol-3-ol, 2-mercaptoacetamide,2-Mercaptoethanol, 1,2-Ethanedithiol, Ammonium thioglycolate,Cysteamine, Methyl thioglycolate, Thiolactic acid,1-Mercapto-2-propanol, 2-methoxyethanethiol, 3-Mercapto-1-propanol,2,3-Dimercapto-1-propanol, 1-Thioglycerol, Mercaptosuccinic acid,4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol, N-Carbamoyl-L-cysteine,2-Methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid,N-Acetylcysteamine, 3-Methyl-1-butanethiol, 1,5-Pentanedithiol,4-Chlorothiophenol, 4-Aminothiophenol, Benzyl mercaptan,2-Furanmethanethiol, 3-Mercaptohexanol, Furfuryl thiol, derivativesthereof, a disulfide complex of one or more thereof, and anycombinations thereof.

In some embodiments of various aspects described herein, the kits canfurther comprise component(s) for performing vacuum assisted closure.Exemplary components can include, but are not limited to a film or thinmaterial (e.g., to seal the wound and create a sub-atmospheric pressureat the local wound environment), a drainage tube that can be connectedto a vacuum source or generator, a vacuum device or apparatus, acontainer (e.g., to collect dissolved hydrogel, blood, fluid exudateand/or any other particulates/materials present on the wound surface),and any combinations thereof.

In addition to the above-mentioned components, the kit can includeinformational material. The informational material can be descriptive,instructional, marketing or other material that relates to the methodsdescribed herein and/or the use/storage of the dissolvable hydrogelcomposition and/or components of the crosslinkable polymers. Forexample, the informational material describes methods to form adissolvable hydrogel using the components of the crosslinkable polymersprovided in the kit; and/or methods to dissolve the dissolvablehydrogel. The kit can also include a delivery device.

In some embodiments, the informational material, e.g., instructions, isprovided in printed matter, e.g., a printed text, drawing, and/orphotograph, e.g., a label or printed sheet. However, the informationalmaterial can also be provided in other formats, such as Braille,computer readable material, video recording, or audio recording. Inanother embodiment, the informational material of the kit is a link orcontact information, e.g., a physical address, email address, hyperlink,website, or telephone number, where a user of the kit can obtainsubstantive information about the formulation and/or its use in themethods described herein. In some embodiments, the informationalmaterial can also be provided in any combination of formats.

In some embodiments, the kit contains separate containers, dividers orcompartments for the pre-formed dissolvable hydrogel or components ofthe crosslinkable polymers and informational material. For example, thepre-formed dissolvable hydrogel or components of the crosslinkablepolymers can be contained in at least one bottle, vial, or syringe, andthe informational material can be contained in a plastic sleeve orpacket. In other embodiments, the separate elements of the kit arecontained within a single, undivided container. For example, thepre-formed dissolvable hydrogel or components of the crosslinkablepolymers is contained in at least one bottle, vial or syringe that hasattached thereto the informational material in the form of a label.

In some embodiments, the kit includes a plurality, e.g., a pack, ofindividual containers, each containing one or more units of thepre-formed dissolvable hydrogel or components of the crosslinkablepolymers. For example, the kit includes a plurality of syringes,ampules, foil packets, or blister packs, each containing a single-useunit of the pre-formed dissolvable hydrogel or components of thecrosslinkable polymers. The containers of the kits can be air tightand/or waterproof.

Exemplary Synthesis of Dissolvable Hydrogels Described Herein

To prepare a dissolvable hydrogel described herein, linear, branched,and/or dendritic-like crosslinkable polymers are crosslinked (e.g., by acovalent bond). For example, the linear, branched and/or dendriticpolymers can be made crosslinkable by chemical modification to have twoor more functional groups that are capable of reacting with functionalgroups present on other linear, branched and/or dendritic crosslinkablepolymers—in one embodiment, thiol (—SH) groups on a first crosslinkablepolymer and an N-hydroxysuccinimide (NHS) or other activated ester on asecond crosslinkable polymer. Each functional group on amultifunctionally linear, branched and/or dendritic crosslinkablepolymer is capable of covalently binding with another crosslinkablepolymer, thereby effecting crosslinking between the polymers andformation of the dissolvable hydrogel described herein.

Examples of covalently crosslinked dissolvable hydrogels can be formedby reacting a crosslinkable polymer comprising activated esters (such asan N-hydroxysuccinimide) with another crosslinkable polymer comprisingthiols. Alternatively, covalently crosslinked dissolvable thioesterhydrogels can be formed by reacting a crosslinkable polymer comprisingmaleimide (MAL) moieties with thioester linkages within its structure,with another crosslinkable polymer comprising thiols. Another example ofcovalently crosslinked dissolvable thioester hydrogels can be formed byreacting a crosslinkable polymer comprising activated esters (such as anN-hydroxysuccinimide) with another crosslinkable polymer comprisingnucleophilic moieties with thioester linkages within its structure.Another example of covalently crosslinked dissolvable thioesterhydrogels can be formed by reacting a crosslinkable polymer comprisingactivated esters (such as an N-hydroxysuccinimide) with thioesterlinkages within its structure with another crosslinkable polymercomprising nucleophilic moieties (e.g., but not limited to, alcohol,amine).

Bioactive Agents, Biologically and/or Pharmaceutically Active Agentsthat can be Used in the Dissolvable Hydrogel and/or CompositionsDescribed Herein

In some embodiments, the dissolvable hydrogel and/or the compositioncomprising the dissolvable hydrogel (e.g., as a layer) can comprise atleast one bioactive agent, including, e.g., at least two, at leastthree, at least four or more bioactive agents. In some embodiments, thebioactive(s) can be incorporated into the dissolvable hydrogel describedherein, and/or other additional layers, if any, present in thecomposition. The bioactive agent(s) can be covalently conjugated to thepolymeric structure of the hydrogel and/or physically entrapped withinthe hydrogel.

In some embodiments, the bioactive agent(s) can be incorporated into thedissolvable hydrogel described herein, and/or other additional layers,if any, present in the composition in an amount between about 0.01% andabout 80% by weight, or between about 1% and about 30%. One of skill inthe art can determine an appropriate loading amount of active agentaccording to various applications and purposes.

A “bioactive agent” refers to an agent that is capable of exerting abiological effect in vitro and/or in vivo. The biological effect can betherapeutic in nature. As used herein, “bioactive agent” refers also toa substance that is used in connection with an application that isdiagnostic in nature, such as in methods for diagnosing the presence orabsence of a disease in a patient. The bioactive agents can be neutralor positively or negatively charged. Examples of suitable bioactiveagents include pharmaceuticals and drugs, cells, gases and gaseousprecursors (e.g., O₂), synthetic organic molecules, proteins, enzymes,growth factors, vitamins, steroids, polyanions, nucleosides,nucleotides, polynucleotides, nanoparticles, and diagnostic agents, suchas contrast agents for use in connection with magnetic resonanceimaging, ultrasound, positron emission tomography (PET), X-ray computedtomography or other imaging modalities.

“Genetic material” refers generally to nucleotides and polynucleotides,including, but not limited to, deoxyribonucleic acid (DNA), any types ofribonucleic acid (RNA) molecules (e.g., but not limited to, siRNA, mRNA,modified RNA, or any combinations thereof), peptide nucleic acid (PNA),and any combinations thereof. The genetic material can be made bysynthetic chemical methodology known to one of ordinary skill in theart, or by the use of recombinant technology, or by a combination of thetwo. The DNA and RNA can optionally comprise unnatural or syntheticnucleotides or analogs and can be single or double stranded. “Geneticmaterial” refers also to sense and anti-sense DNA and RNA, that is, anucleotide sequence that is complementary to a specific sequence ofnucleotides in DNA and/or RNA.

Examples of bioactive agents for use in the dissolvable hydrogel and/orcompositions described herein include, without limitations, medicaments;vitamins; mineral supplements; substances used for the treatment,prevention, diagnosis, cure or mitigation of disease or illness; orsubstances which attest the structure or function of the body; orpro-drugs, which become biologically active or more active after theyhave been placed in a predetermined physiological environment. In someembodiments, bioactive agent(s) include, but are not limited to, growthfactors, such as members of the transforming growth factor (TGF) genefamily (e.g., TGF-β1, TGF-β2, and TGF-β3), fibroblast growth factors(FGFs), platelet derived growth factors (PDGFs), epidermal growthfactors (EGFs), connective tissue activated peptides (CTAPs), osteogenicfactors, bone morphogenetic proteins (for example, BMP-1, BMP-2, BMP-3,BMP-4, BMP-5, BMP-6, BMP-7, BMP-8, BMP-9); heparin-binding growthfactors (for example, fibroblast growth factor (FGF), epidermal growthfactor (EGF), platelet-derived growth factor (PDGF), insulin-like growthfactor (IGF)); Inhibins (for example, Inhibin A, Inhibin B); growthdifferentiating factors (for example, GDF-1); and Activins (for example,Activin A, Activin B, Activin AB), vascular endothelium growth factor(VEGF); hormones, e.g., but not limited to, insulin, glucagon, andestrogen; therapeutic agents or drugs, e.g., but not limited towound-healing agents, anti-inflammatory steroids, and chemotherapeutics;antimicrobial agents; an anesthetic; and biologically active analogs,fragments, and derivatives of such growth factors; and any combinationsthereof.

In some embodiments, the bioactive agent(s) can be pharmaceuticallyactive agent(s). Non-limiting examples of the pharmaceutically activeagent(s) can include (1) nonsteroidal anti-inflammatory drugs (NSAIDs)analgesics, including but not limited to diclofenac, ibuprofen,ketoprofen, and naproxen; (2) opiate agonist analgesics, including butnot limited to codeine, vancomycin, ceftazidime, fentanyl,hydromorphone, and morphine; (3) salicylate analgesics, including butnot limited to aspirin (ASA) (or enteric coated ASA); (4) H1-blockerantihistamines, including but not limited to clemastine and terfenadine;(5) H2-blocker antihistamines, including but not limited to cimetidine,famotidine, nizadine, and ranitidine; (6) anti-infective agents,including but not limited to mupirocin; (7) antianaerobicanti-infectives, including but not limited to chloramphenicolmetronidazole and clindamycin; (8) antifungal antibioticanti-infectives, including but not limited to amphotericin B,clotrimazole, fluconazole, and ketoconazole; (9) macrolide antibioticanti-infectives, including but not limited to azithromycin anderythromycin; (10) miscellaneous beta-lactam antibiotic anti-infectives,including but not limited to aztreonam and imipenem; (11) penicillinantibiotic anti-infectives, including but not limited to nafcillin,oxacillin, penicillin G, and penicillin V; (12) quinolone antibioticanti-infectives, including but not limited to ciprofloxacin andnorfloxacin; (13) tetracycline antibiotic anti-infectives, including butnot limited to doxycycline, minocycline, and tetracycline; (14)antituberculosis antimycobacterial anti-infectives including but notlimited to isoniazid (INH), and rifampin; (15) antiprotozoalanti-infectives, including but not limited to atovaquone and dapsone;(16) antimalarial antiprotozoal anti-infectives, including but notlimited to chloroquine and pyrimethamine; (17) anti-retroviralanti-infectives, including but not limited to ritonavir and zidovudine;(18) antiviral anti-infective agents, including but not limited toacyclovir, ganciclovir, interferon alpha, and rimantadine; (19)alkylating antineoplastic agents, including but not limited tocarboplatin and cisplatin; (20) nitrosourea alkylating antineoplasticagents, including but not limited to carmustine (BCNU); (21)antimetabolite antineoplastic agents, including but not limited tomethotrexate; (22) pyrimidine analog antimetabolite antineoplasticagents, including but not limited to fluorouracil (5-FU), gemcitabine,or ceftazidine, aminoglycodi meroperium, or ticarcillin and tobramycin;(23) hormonal antineoplastics, including but not limited to goserelin,leuprolide, and tamoxifen; (24) natural antineoplastics, including butnot limited to aldesleukin, interleukin-2, docetaxel, etoposide (VP-16),interferon alpha, paclitaxel, and tretinoin (ATRA); (25) antibioticnatural antineoplastics, including but not limited to bleomycin,actinomycin, daunorubicin, doxorubicin, and mitomycin; (26) vincaalkaloid natural antineoplastics, including but not limited tovinblastine and vincristine; (27) autonomic agents, including but notlimited to nicotine; (28) anticholinergic autonomic agents, includingbut not limited to benztropine and trihexyphenidyl; (29) antimuscarinicanticholinergic autonomic agents, including but not limited to atropineand oxybutynin; (30) ergot alkaloid autonomic agents, including but notlimited to bromocriptine; (31) cholinergic agonist parasympathomimetics,including but not limited to pilocarpine; (32) cholinesterase inhibitorparasympathomimctics, including but not limited to pyridostigmine; (33)alpha-blocker sympatholytics, including but not limited to prazosin;(34) beta-blocker sympatholytics, including but not limited to atenolol;(35) adrenergic agonist sympathomimetics, including but not limited toalbuterol and dobutamine; (36) cardiovascular agents, including but notlimited to aspirin (ASA), plavix (Clopidogrel bisulfate) etc; (37)beta-blocker antianginals, including but not limited to atenolol andpropranolol; (38) calcium-channel blocker antianginals, including butnot limited to nifedipine and verapamil; (39) nitrate antianginals,including but not limited to isosorbide dinitrate (ISDN); (40) cardiacglycoside antiarrhythmics, including but not limited to digoxin; (41)class I anti-arrhythmics, including but not limited to lidocaine,mexiletine, phenytoin, procainamide, and quinidine; (42) class IIantiarrhythmics, including but not limited to atenolol, metoprolol,propranolol, and timolol; (43) class III antiarrhythmics, including butnot limited to amiodarone; (44) class TV antiarrhythmics, including butnot limited to diltiazem and verapamil; (45) alpha-blockerantihypertensives, including but not limited to prazosin; (46)angiotensin-converting enzyme inhibitor (ACE inhibitor)antihypertensives, including but not limited to captopril and enalapril;(47) beta blocker antihypertensives, including but not limited toatenolol, metoprolol, nadolol, and propanolol; (48) calcium-channelblocker antihypertensive agents, including but not limited to diltiazemand nifedipine; (49) central-acting adrenergic antihypertensives,including but not limited to clonidine and methyldopa; (50) diureticantihypertensive agents, including but not limited to amiloride,furosemide, hydrochlorothiazide (HCTZ), and spironolactone; (51)peripheral vasodilator antihypertensives, including but not limited tohydralazine and minoxidil; (52) antilipemics, including but not limitedto gemfibrozil and probucol; (53) bile acid sequestrant antilipemics,including but not limited to cholestyramine; (54) HMG-CoA reductaseinhibitor antilipemics, including but not limited to lovastatin andpravastatin; (55) inotropes, including but not limited to amrinone,dobutamine, and dopamine; (56) cardiac glycoside inotropes, includingbut not limited to digoxin; (57) thrombolytic agents or enzymes,including but not limited to alteplase (TPA), anistreplase,streptokinase, and urokinase; (58) dermatological agents, including butnot limited to colchicine, isotretinoin, methotrexate, minoxidil,tretinoin (ATRA); (59) dermatological corticosteroid anti-inflammatoryagents, including but not limited to betamethasone and dexamethasone;(60) antifungal topical antiinfectives, including but not limited toamphotericin B, clotrimazole, miconazole, and nystatin; (61) antiviraltopical anti-infectives, including but not limited to acyclovir; (62)topical antineoplastics, including but not limited to fluorouracil(5-FU); (63) electrolytic and renal agents, including but not limited tolactulose; (64) loop diuretics, including but not limited to furosemide;(65) potassium-sparing diuretics, including but not limited totriamterene; (66) thiazide diuretics, including but not limited tohydrochlorothiazide (HCTZ); (67) uricosuric agents, including but notlimited to probenecid; (68) enzymes including but not limited to RNaseand DNase; (69) immunosupressive agents, including but not limited tocyclosporine, steroids, methotrexate, tacrolimus, sirolimus, rapamycin;(70) antiemetics, including but not limited to prochlorperazine; (71)salicylate gastrointestinal anti-inflammatory agents, including but notlimited to sulfasalazine; (72) gastric acid-pump inhibitor anti-ulceragents, including but not limited to omeprazole; (73) H2-blockeranti-ulcer agents, including but not limited to cimetidine, famotidine,nizatidine, and ranitidine; (74) digestants, including but not limitedto pancrelipase; (75) prokinetic agents, including but not limited toerythromycin; (76) opiate agonist intravenous anesthetics including butnot limited to fentanyl; (77) hematopoietic antianemia agents, includingbut not limited to erythropoietin, filgrastim (G-CSF), and sargramostim(GM-CSF); (78) coagulation agents, including but not limited toantihemophilic factors 1-10 (AHF 1-10); (79) anticoagulants, includingbut not limited to warfarin, heparin (important for heparin boundpolymers and cardiopulmonary bypass pump circuits), argatroban—eachworks by a different mechanism and is metabolized differently; (80)growth receptor inhibitors, including but not limited to erlotinib andgefetinib; (82) abortifacients, including but not limited tomethotrexate; (83) antidiabetic agents, including but not limited toinsulin; (84) oral contraceptives, including but not limited to estrogenand progestin; (85) progestin contraceptives, including but not limitedto levonorgestrel and norgestrel; (86) estrogens including but notlimited to conjugated estrogens, diethylstilbestrol (DES), estrogen(estradiol, estrone, and estropipate); (87) fertility agents, includingbut not limited to clomiphene, human chorionic gonadatropin (HCG), andmenotropins; (88) parathyroid agents including but not limited tocalcitonin; (89) pituitary hormones, including but not limited todesmopressin, goserelin, oxytocin, and vasopressin (ADH); (90)progestins, including but not limited to medroxyprogesterone,norethindrone, and progesterone; (91)thyroid hormones, including but notlimited to levothyroxine; (92) immunobiologic agents, including but notlimited to interferon beta-1b and interferon gamma-1b; (93)immunoglobulins, including but not limited to immune globulin IM, IMIG,IGIM and immune globulin IV, IVIG, IGIV; (94) amide local anesthetics,including but not limited to lidocaine; (95) ester local anesthetics,including but not limited to benzocaine and procaine; (96)musculoskeletal corticosteroid anti-inflammatory agents, including butnot limited to beclomethasone, betamethasone, cortisone, dexamethasone,hydrocortisone, and prednisone; (97) musculoskeletal anti-inflammatoryimmunosuppressives, including but not limited to azathioprine,cyclophosphamide, and methotrexate; (98) musculoskeletal nonsteroidalanti-inflammatory drugs (NSAIDs), including but not limited todiclofenac, ibuprofen, ketoprofen, ketorlac, and naproxen; (99) skeletalmuscle relaxants, including but not limited to baclofen,cyclobenzaprine, and diazepam; (100) reverse neuromuscular blockerskeletal muscle relaxants, including but not limited to pyridostigmine;(101) neurological agents, including but not limited to nimodipine,riluzole, tacrine and ticlopidine; (102) anticonvulsants, including butnot limited to carbamazepine, gabapentin, lamotrigine, phenytoin, andvalproic acid; (103) barbiturate anticonvulsants, including but notlimited to phenobarbital and primidone; (104) benzodiazepineanticonvulsants, including but not limited to clonazepam, diazepam, andlorazepam; (105) anti-parkisonian agents, including but not limited tobromocriptine, levodopa, carbidopa, and pergolide; (106) anti-vertigoagents, including but not limited to meclizine; (107) opiate agonists,including but not limited to codeine, fentanyl, hydromorphone,methadone, and morphine; (108) opiate antagonists, including but notlimited to naloxone; (109) beta-blocker anti-glaucoma agents, includingbut not limited to timolol; (110) miotic anti-glaucoma agents, includingbut not limited to pilocarpine; (111) ophthalmic aminoglycosideantiinfectives, including but not limited to gentamicin, neomycin, andtobramycin; (112) ophthalmic quinolone anti-infectives, including butnot limited to ciprofloxacin, norfloxacin, and ofloxacin; (113)ophthalmic corticosteroid anti-inflammatory agents, including but notlimited to dexamethasone and prednisolone; (114) ophthalmic nonsteroidalanti-inflammatory drugs (NSAIDs), including but not limited todiclofenac; (115) antipsychotics, including but not limited toclozapine, haloperidol, and risperidone; (116) benzodiazepineanxiolytics, sedatives and hypnotics, including but not limited toclonazepam, diazepam, lorazepam, oxazepam, and prazepam; (117)psychostimulants, including but not limited to methylphenidate andpemoline; (118) antitussives, including but not limited to codeine;(119) bronchodilators, including but not limited to theophylline; (120)adrenergic agonist bronchodilators, including but not limited toalbuterol; (121) respiratory corticosteroid anti-inflammatory agents,including but not limited to dexamethasone; (122) antidotes, includingbut not limited to flumazenil and naloxone; (123) heavy metalantagonists/chelating agents, including but not limited topenicillamine; (124) deterrent substance abuse agents, including but notlimited to disulfiram, naltrexone, and nicotine; (125) withdrawalsubstance abuse agents, including but not limited to bromocriptine;(126) minerals, including but not limited to iron, calcium, andmagnesium; (127) vitamin B compounds, including but not limited tocyanocobalamin (vitamin B12) and niacin (vitamin B3); (128) vitamin Ccompounds, including but not limited to ascorbic acid; (129) vitamin Dcompounds, including but not limited to calcitriol; (130) antiparasiticcompounds including but not limited to metronidazole; (131)bronchodilators, including but not limited to salmeterol, and betaagonists; (132) leukotriene blockers/modifiers including montelukast orzileuton; (133) inhaled steroids including but not limited tofluticasone, beclomethasone, or budesonide. Anti-bleeding (hemostatic)agents including but not limited to protamine and antihelminth,radiation sensitizers, and other drugs including but not limited toracin and cyclosporine are also included. Additional anticancer drugsincluding but not limited to pycnidione as well as anti-Myc inhibitors.Nanoparticles can comprise silver or silver salts for antibacterialactivity.

In addition to the foregoing, the following pharmaceutically activeagents can also be used in the dissolvable hydrogels and/or compositionsdescribed herein, which include, but are not limited to, chlorhexidine;estradiol cypionate in oil; estradiol valerate in oil; flurbiprofen;flurbiprofen sodium; ivermectin; levodopa; nafarelin; and somatropin.Further, the following drugs can also be used: pycnidione, cyclosporine,recombinant beta-glucan; bovine immunoglobulin concentrate; bovinesuperoxide dismutase; the formulation comprising fluorouracil,epinephrine, and bovine collagen; recombinant hirudin (r-Hir), HIV-1immunogen; human anti-TAC antibody; recombinant human growth hormone(r-hGH); recombinant human hemoglobin (r-Hb); recombinant humanmecasermin (r-IGF-1); recombinant interferon beta-1a; lenograstim(G-CSF); olanzapine; recombinant thyroid stimulating hormone (r-TSH);and topotecan. Further still, the following intravenous products can beused: acyclovir sodium; aldesleukin; atenolol; bleomycin sulfate, humancalcitonin; salmon calcitonin; carboplatin; carmustine; dactinomycin,daunorubicin HCl; docetaxel; doxorubicin HCl; epoetin alfa; etoposide(VP-16); fluorouracil (5-FU); ganciclovir sodium; gentamicin sulfate;interferon alpha; leuprolide acetate; meperidine HCl; methadone HCl;methotrexate sodium; paclitaxel; ranitidine HCl; vinblastin sulfate; andzidovudine (AZT).

Further examples of pharmaceutically active agents from the abovecategories include: (a) anti-neoplastics including but not limited toandrogen inhibitors, antimetabolites, cytotoxic agents, receptorinhibitors, and immunomodulators; (b) anti-tussives including but notlimited to dextromethorphan, dextromethorphan hydrobromide, noscapine,carbetapentane citrate, and chlorphedianol hydrochloride; (c)antihistamines including but not limited to chlorpheniramine maleate,phenindamine tartrate, pyrilamine maleate, doxylamine succinate, andphenyltoloxamine citrate; (d) decongestants including but not limited tophenylephrine hydrochloride, phenylpropanolamine hydrochloride,pseudophedrine hydrochloride, and ephedrine; (e) various alkaloidsincluding but not limited to codeine phosphate, codeine sulfate andmorphine; (f) mineral supplements including but not limited to potassiumchloride, zinc chloride, calcium carbonates, magnesium oxide, and otheralkali metal and alkaline earth metal salts; (g) ion exchange resinsincluding but not limited to cholestryramine; (h) anti-arrhythmicsincluding but not limited to N-acetylprocainamide; (i) antipyretics andanalgesics including but not limited to acetaminophen, aspirin andibuprofen; (j) appetite suppressants including but not limited tophenyl-propanolamine hydrochloride or caffeine; (k) expectorantsincluding but not limited to guaifenesin; (l) antacids including but notlimited to aluminum hydroxide and magnesium hydroxide; (m) biologicalsincluding but not limited to peptides, polypeptides, proteins and aminoacids, hormones, interferons or cytokines, and other bioactive peptidiccompounds, including but not limited to interleukins 1-18 includingmutants and analogues, RNase, DNase, luteinizing hormone releasinghormone (LHRH) and analogues, gonadotropin releasing hormone (GnRH),transforming growth factor-.beta. (TGF-beta), fibroblast growth factor(FGF), tumor necrosis factor-alpha & beta (TNF-alpha & beta), nervegrowth factor (NGF), growth hormone releasing factor (GHRF), epidermalgrowth factor (EGF), fibroblast growth factor homologous factor (FGFHF),hepatocyte growth factor (HGF), insulin growth factor (IGF), invasioninhibiting factor-2 (IIF-2), bone morphogenetic proteins 1-7 (BMP 1-7),somatostatin, thymosin-alpha-1, gamma-globulin, superoxide dismutase(SOD), complement factors, hGH, tPA, calcitonin, ANF, EPO and insulin;and (n) anti-infective agents including but not limited to antifungals,anti-bacterials (including, e.g., silver nanoparticles), anti-virals,antihelminths, antiseptics and antibiotics. Additional agents includehemoglobin, oxygen, nitric oxide, silver or other noble metals or ionsthereof (e.g., silver nanoparticles, rods, crystals and other structuresor silver salts). Additional agents include drugs that have renaltoxicity and cardio toxicity, wherein the delivery with the particlesassists in reducing the renal or cardiotoxicity by delivering the drugsin a targeted manner to a tissue site other than kidneys or the heart.

Examples of specific drugs that can be used include, but are not limitedto asparaginase; bleomycin; busulfan; capecitabine; carboplatin;carmustine; chlorambucil; cisplatin; cyclophosphamide; cytarabine;dacarbizine; dactinomycin; daunorubicin; dexrazoxane; docetaxel;doxorubicin; erlotinibil/gefctinib; etoposide; floxuridine; fludarabine;fluoruracil; gemcitabine; 10-hydrocamptothecin; hydroxyurea; idarubicin;ifosfamide; irinotecan; lomustine; mechlorethamine; melphalan;mercaptopurine; methotrexate; mitomycin; mitotane; mitoxantrone;paclitaxel; pentostatin; plicamycin; pemextred procarbazine; rituximabe;streptozocin; teniposid; thioguanine; thiotepa; vinplastine,vinchristine; and vinorelbineor derivates of these molecules.

Examples of anticancer, antineoplastic agents are camptothecins. Thesedrugs are antineoplastic by virtue of their ability to inhibittopoisomerase I. Camptothecin is a plant alkaloid isolated from treesindigenous to China and analogs thereof including but not limited to9-aminocamptothecin, 9-nitrocamptothecin, 10-hydroxycamptothecin,10,11-methylenedioxycamptothecin, 9-nitro10,11-methylenehydroxycamptothecin,9-chloro-10,11-methylenehydroxycamptothecin,9-amino-10,11-methylenehydroxycamptothecin,7-ethyl-10-hydroxycamptothecin (SN-38), topotecan, DX-8951, Lurtotecan(GII147221C), and other analogs (collectively referred to herein ascamptothecin drugs) are presently under study worldwide in researchlaboratories for treatment of colon, breast, and other cancers.

Additionally, the pharmaceutically active agent can be aradiosensitizer, including but not limited to metoclopramide, sensamideor neusensamide (manufactured by Oxigene); profiromycin (made by Vion);RSR13 (made by Allos); THYMITAQ® (made by Agouron), etanidazole orlobenguane (manufactured by Nycomed); gadolinium texaphrin (made byPharmacyclics); BuDR/Broxine (made by NeoPharm); IPdR (made by Sparta);CR2412 (made by Cell Therapeutic); L1X (made by Terrapin); agents thatminimize hypoxia, and the like. The biologically active substance can beselected from the group consisting of peptides, polypeptides, proteins,amino acids, polysaccharides, growth factors, hormones,anti-angiogenesis factors, interferons or cytokines, elements, andpro-drugs. In one embodiment, the biologically active substance is atherapeutic drug or pro-drug, most preferably a drug selected from thegroup consisting of chemotherapeutic agents and other antineoplasticsincluding but not limited to paclitaxel, carboplatin and cisplatin;nitrosourea alkylating antineoplastic agents, including but not limitedto carmustine (BCNU); fluorouracil (5-FU) and gemcitabine; hormonalantineoplastics, including but not limited to goserelin, leuprolide, andtamoxifen; receptor inhibitors including but not limited to erlotinib,gefetinib, Sunitinib, Imatinib, or anti-ckit inhibitors (registered nameis Gleevec); natural antineoplastics, including but not limited toaldesleukin, interleukin-2, docetaxel, etoposide (VP-16), interferonalpha, paclitaxel, and tretinoin (ATRA)carboplatin and cisplatin;nitrosourea alkylating antineoplastic agents, including but not limitedto carmustine (BCNU); fluorouracil (5-FU) and gemcitabine; hormonalantineoplastics, including but not limited to goserelin, leuprolide, andtamoxifen; receptor inhibitors including but not limited to erlotinib,gefetinib, Sunitinib, Imatinib, or anti-ckit inhibitors (registered nameis Gleevec); natural antineoplastics, including but not limited toaldesleukin, interleukin-2, docetaxel, etoposide (VP-16), interferonalpha, paclitaxel, and tretinoin (ATRA), antibiotics, anti-virals,antifungals, anesthetics, antihelminths, anti-inflammatories, andanticoagulants.

In some embodiments, the bioactive agent(s) to be delivered is dissolvedin an aqueous solution or in an aqueous solution containing anothercompound to increase the agent's solubility including but not limited toCremaphor E/L for paclitaxel.

Non-limiting examples of additional pharmaceutically active agentsinclude the following therapeutic categories: anabolic agents,anesthetic agents, antacids, anti-asthmatic agents, anticholesterolemicand anti-lipid agents, anti-coagulants, anti-convulsants,anti-diarrheals, antiemetics, anti-infective agents, anti-inflammatoryagents, anti-manic agents, anti-nauseants, antineoplastic agents,anti-obesity agents, anti-pyretic and analgesic agents, anti-spasmodicagents, anti-thrombotic agents, anti-uricemic agents, anti-anginalagents, antihistamines, anti-tussives, appetite suppressants,biologicals, cerebral dilators, coronary dilators, decongestants,diuretics, diagnostic agents, erythropoietic agents, expectorants,gastrointestinal sedatives, hyperglycemic agents, hypnotics,hypoglycemic agents, ion exchange resins, laxatives, mineralsupplements, mucolytic agents, neuromuscular drugs, peripheralvasodilators, psychotropics, sedatives, small molecule inhibitors,receptor enzysmes, stimulants, thyroid and anti-thyroid agents, uterinerelaxants, vitamins, and prodrugs.

More specifically, non-limiting examples of pharmaceutically activeagents include the following therapeutic categories: analgesics,including but not limited to nonsteroidal anti-inflammatory drugs,opiate agonists and salicylates; antihistamines, including but notlimited to H1-blockers and H2-blockers; anti-infective agents, includingbut not limited to anthelmintics, antianaerobics, antibiotics,aminoglycoside antibiotics, antifungal antibiotics, cephalosporinantibiotics, macrolide antibiotics, miscellaneous beta-lactamantibiotics, penicillin antibiotics, quinolone antibiotics, sulfonamideantibiotics, tetracycline antibiotics, antimycobacterials,antituberculosis antimycobacterials, antiprotozoals, antimalarialantiprotozoals, antiviral agents, anti-retroviral agents, scabicides,and urinary anti-infectives; antineoplastic agents, including but notlimited to alkylating agents, nitrogen mustard aklylating agents,nitrosourea alkylating agents, antimetabolites, purine analogantimetabolites, pyrimidine analog antimetabolites, hormonalantineoplastics, natural antineoplastics, antibiotic naturalantineoplastics, and vinca alkaloid natural antineoplastics; autonomicagents, including but not limited to anticholinergics, antimuscarinicanticholinergics, ergot alkaloids, parasympathomimetics, cholinergicagonist parasympathomimetics, cholinesterase inhibitorpara-sympathomimetics, sympatholytics, alpha-blocker sympatholytics,beta-blocker sympatholytics, sympathomimetics, and adrenergic agonistsympathomimetics; cardiovascular agents, including but not limited toantianginals, betablocker antianginals, calcium-channel blockerantianginals, nitrate antianginals, antiarrhythmics, cardiac glycosideantiarrhythmics, class I antiarrhythmics, class II antiarrhythmics,class III antiarrhythmics, class N antiarrhythmics, antihypertensiveagents, alpha-blocker antihypertensives, angiotensin-converting enzymeinhibitor (ACE inhibitor) antihypertensives, beta-blockerantihypertensives, calcium-channel blocker antihypertensives,central-acting adrenergic antihypertensives, diuretic antihypertensiveagents, peripheral vasodilator antihypertensives, antilipemics, bileacid sequestrant antilipemics, IIMG-CoA reductase inhibitorantilipemics, inotropes, cardiac glycoside inotropes, and thrombolyticagents; dermatological agents, including but not limited toantihistamines, anti-inflammatory agents, corticosteroidanti-inflammatory agents, antipruritics/local anesthetics, topicalanti-infectives, antifungal topical anti-infectives, antiviral topicalanti-infectives, and topical antineoplastics; electrolytic and renalagents, including but not limited to acidifying agents, alkalinizingagents, diuretics, carbonic anhydrase inhibitor diuretics, loopdiuretics, osmotic diuretics, potassium-sparing diuretics, thiazidediuretics, electrolyte replacements, and uricosuric agents; enzymes,including but not limited to pancreatic enzymes and thrombolyticenzymes; gastrointestinal agents, including but not limited toantidiarrheals, antiemetics, gastrointestinal anti-inflammatory agents,salicylate gastrointestinal anti-inflammatory agents, antacid anti-ulceragents, gastric acid-pump inhibitor anti-ulcer agents, gastric mucosalanti-ulcer agents, H2-blocker anti-ulcer agents, cholelitholytic agents,digestants, emetics, laxatives and stool softeners, and prokineticagents; general anesthetics, including but not limited to inhalationanesthetics, halogenated inhalation anesthetics, intravenousanesthetics, barbiturate intravenous anesthetics, benzodiazepineintravenous anesthetics, and opiate agonist intravenous anesthetics;hematological agents, including but not limited to antianemia agents,hematopoietic antianemia agents, coagulation agents, anticoagulants,hemostatic coagulation agents, platelet inhibitor coagulation agents,thrombolytic enzyme coagulation agents, and plasma volume expanders;hormones and hormone modifiers, including but not limited toabortifacients, adrenal agents, corticosteroid adrenal agents,androgens, antiandrogens, antidiabetic agents, sulfonylurea antidiabeticagents, antihypoglycemic agents, oral contraceptives, progestincontraceptives, estrogens, fertility agents, oxytocics, parathyroidagents, pituitary hormones, progestins, antithyroid agents, thyroidhormones, and tocolytics; immunobiologic agents, including but notlimited to immunoglobulins, immunosuppressives, toxoids, and vaccines;local anesthetics, including but not limited to amide local anestheticsand ester local anesthetics; musculoskeletal agents, including but notlimited to anti-gout anti-inflammatory agents, corticosteroidanti-inflammatory agents, gold compound anti-inflammatory agents,immuno-suppressive anti-inflammatory agents, nonsteroidalanti-inflammatory drugs (NSAIDs), salicylate anti-inflammatory agents,skeletal muscle relaxants, neuromuscular blocker skeletal musclerelaxants, and reverse neuromuscular blocker skeletal muscle relaxants;neurological agents, including but not limited to anticonvulsants,barbiturate anticonvulsants, benzodiazepine anticonvulsants,anti-migraine agents, anti-parkinsonian agents, anti-vertigo agents,opiate agonists, and opiate antagonists; ophthalmic agents, includingbut not limited to antiglaucoma agents, beta-blocker anti gluacomaagents, miotic anti-glaucoma agents, mydriatics, adrenergic agonistmydriatics, antimuscarinic mydriatics, ophthalmic anesthetics,ophthalmic anti-infectives, ophthalmic aminoglycoside anti-infectives,ophthalmic macrolide anti-infectives, ophthalmic quinoloneanti-infectives, ophthalmic sulfonamide anti-infectives, ophthalmictetracycline anti-infectives, ophthalmic anti-inflammatory agents,ophthalmic corticosteroid anti-inflammatory agents, and ophthalmicnonsteroidal anti-inflammatory drugs (NSAIDs); psychotropic agents,including but not limited to antidepressants, heterocyclicantidepressants, monoamine oxidase inhibitors (MAOIs), sclerosantsincluding but not limited to talc, alcohol or doxycyclin, selectiveserotonin re-uptake inhibitors (SSRIs), tricyclic antidepressants,antimanics, antipsychotics, phenothiazine antipsychotics, anxiolytics,sedatives, and hypnotics, barbiturate sedatives and hypnotics,benzodiazepine anxiolytics, sedatives, and hypnotics, andpsychostimulants; respiratory agents, including but not limited toantitussives, bronchodilators, adrenergic agonist bronchodilators,antimuscarinic bronchodilators, expectorants, mucolytic agents,respiratory anti-inflammatory agents, leukotriene modifiers andrespiratory corticosteroid anti-inflammatory agents; toxicology agents,including but not limited to antidotes, heavy metalantagonists/chelating agents, substance abuse agents, deterrentsubstance abuse agents, and withdrawal substance abuse agents; minerals;and vitamins, including but not limited to vitamin A, vitamin B, vitaminC, vitamin D, vitamin E, and vitamin K.

In some embodiments, the pharmaceutically active agents can include anantimicrobial agent. The term “antimicrobial agent” as used hereinrefers to any entity with antimicrobial activity, i.e. the ability toinhibit or reduce the growth and/or kill a microbe, for example,bacteria. In various embodiments, the antimicrobial agent can be acompound (e.g., antibiotics or antiseptic agent) indicated for treatmentof a bacterial infection in a human or veterinary subject.

In some embodiments, an antimicrobial agent can be an antibiotic. Asused herein, the term “antibiotic” is art recognized and includesantimicrobial agents naturally produced by microorganisms such asbacteria (including Bacillus species), actinomycetes (includingStreptomyces) or fungi that inhibit growth of or destroy other microbes,or genetically-engineered thereof and isolated from such natural source.Substances of similar structure and mode of action can be synthesizedchemically, or natural compounds can be modified to producesemi-synthetic antibiotics.

Additional examples of antimicrobial agents include, but are not limitedto, silver nanoparticles, rods, crystals, or any other structures,and/or silver salts.

Pharmaceutical Compositions

As used herein, the term “pharmaceutical composition” refers to achemical compound or composition capable of inducing a desiredtherapeutic effect in a subject. In some embodiments, a pharmaceuticalcomposition comprises a pre-formed dissolvable hydrogel describedherein. In some embodiments, a pharmaceutical composition comprisescomponents of the linear, branched and/or dendritic crosslinkablepolymers described herein to be applied to a target site (e.g., a wound)to form a dissolvable hydrogel described herein in situ at the targetsite (e.g., a wound). In certain embodiments, a pharmaceuticalcomposition comprises a therapeutically effective amount of a bioactiveagent described herein distributed in one or more embodiments of thedissolvable hydrogel described herein. In some embodiments, thepharmaceutical composition can comprise a prodrug of the compoundsprovided herein. In certain embodiments, a pharmaceutical compositioncan comprise inactive ingredients, such as, for example, carriers andexcipients.

The phrase “therapeutically effective amount” refers to the amount of apharmaceutical composition that elicits the biological or medicinalresponse in a tissue, system, animal, individual, patient, or human thatis being sought by a researcher, veterinarian, medical doctor or otherclinician.

As used herein, the term “pharmaceutically acceptable” refers to aformulation of a compound that does not significantly abrogate thebiological activity, a pharmacological activity and/or other propertiesof the compound when the formulated compound is administered to asubject. In certain embodiments, a pharmaceutically acceptableformulation does not cause significant irritation to a subject.

As used herein, pharmaceutically acceptable derivatives of a compoundinclude, but are not limited to, salts, esters, enol ethers, enolesters, acetals, ketals, orthoesters, hemiacetals, hemiketals, acids,bases, solvates, hydrates, PEGylation, or prodrugs thereof. Suchderivatives can be readily prepared by those of skill in this art usingknown methods for such derivatization. The compounds produced can beadministered to animals or humans without substantial toxic effects andare either pharmaceutically active or prodrugs. Pharmaceuticallyacceptable salts include, but are not limited to, amine salts, such asbut not limited to chloroprocaine, choline,N,N′-dibenzyl-ethylenediamine, ammonia, diethanolamine and otherhydroxyalkylamines, ethylenediamine, N-methylglucamine, procaine,N-benzyl-phenethylamine,1-para-chloro-benzyl-2-pyrrolidin-1′-ylmethyl-benzimidazole,diethylamine and other alkylamines, piperazine andtris(hydroxymethyl)-aminomethane; alkali metal salts, such as but notlimited to lithium, potassium and sodium; alkali earth metal salts, suchas but not limited to barium, calcium and magnesium; transition metalsalts, such as but not limited to zinc; and other metal salts, such asbut not limited to sodium hydrogen phosphate and disodium phosphate; andalso including, but not limited to, salts of mineral acids, such as butnot limited to hydrochlorides and sulfates; and salts of organic acids,such as but not limited to acetates, lactates, malates, tartrates,citrates, ascorbates, succinates, butyrates, valerates and fumarates.Pharmaceutically acceptable esters include, but are not limited to,alkyl, alkenyl, alkynyl, aryl, heteroaryl, aralkyl, heteroaralkyl,cycloalkyl and heterocyclyl esters of acidic groups, including, but notlimited to, carboxylic acids, phosphoric acids, phosphinic acids,sulfonic acids, sulfinic acids and boronic acids. Pharmaceuticallyacceptable enol ethers include, but are not limited to, derivatives offormula C═C(OR) where R is hydrogen, alkyl, alkenyl, alkynyl, aryl,heteroaryl, aralkyl, heteroaralkyl, cycloalkyl, or heterocyclyl.Pharmaceutically acceptable enol esters include, but are not limited to,derivatives of formula C═C(OC(O)R) where R is hydrogen, alkyl, alkenyl,alkynyl, aryl, heteroaryl, aralkyl, heteroaralkyl, cycloalkyl, orheterocyclyl. Pharmaceutically acceptable solvates and hydrates arecomplexes of a compound with one or more solvent or water molecules, orone to about 100, or one to about 10, or one to about two, three, orfour, solvent or water molecules.

In some embodiments, the pharmaceutical composition can further comprisea pharmaceutically-acceptable carrier. As used here, the term“pharmaceutically-acceptable carrier” means apharmaceutically-acceptable material, composition or vehicle, such as aliquid or solid filler, diluent, excipient, manufacturing aid (e.g.,lubricant, talc magnesium, calcium or zinc stearate, or steric acid), orsolvent encapsulating material, involved in carrying or transporting thesubject compound from one organ, or portion of the body, to anotherorgan, or portion of the body. Each carrier must be “acceptable” in thesense of being compatible with the other ingredients of the formulationand not injurious to the patient. Some examples of materials which canserve as pharmaceutically-acceptable carriers include: (1) sugars, suchas lactose, mannose, fructose, dextrose, trehalose, glucose and sucrose;(2) starches, such as corn starch and potato starch; (3) cellulose, andits derivatives, such as sodium carboxymethyl cellulose,methylcellulose, ethyl cellulose, microcrystalline cellulose andcellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7)lubricating agents, such as magnesium stearate, sodium lauryl sulfateand talc; (8) excipients, such as cocoa butter and suppository waxes;(9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil,olive oil, corn oil and soybean oil; (10) glycols, such as propyleneglycol; (11) polyols, such as glycerin, sorbitol, mannitol andpolyethylene glycol (PEG); (12) esters, such as ethyl oleate and ethyllaurate; (13) agar; (14) buffering agents, such as magnesium hydroxideand aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17)isotonic saline; (18) Ringer's solution; (19) ethyl alcohol; (20) pHbuffered solutions; (21) polyesters, polycarbonates and/orpolyanhydrides; (22) bulking agents, such as polypeptides and aminoacids (23) serum component, such as scrum albumin, HDL and LDL; (22)C₂-C₁₂ alcohols, such as ethanol; and (23) other non-toxic compatiblesubstances employed in pharmaceutical formulations. Wetting agents,coloring agents, release agents, coating agents, sweetening agents,flavoring agents, perfuming agents, preservative and antioxidants canalso be present in the formulation. The terms such as “excipient”,“carrier”, “pharmaceutically acceptable carrier” or the like are usedinterchangeably herein.

As used herein, the term “administer” refers to the placement of acomposition into a subject by a method or route which results in atleast partial localization of the composition at a desired site suchthat desired effect is produced. Examples of administration routes caninclude, but are not limited to, transdermal, topical (including buccaland sublingual) administration and/or by surgery.

In some embodiments, the pharmaceutical composition comprisingcomponents of the crosslinkable polymers can be administered to a targetsite (e.g., a wound) by injection such that a dissolvable hydrogel canform in situ at the target site (e.g., a wound). In some embodiments,the pharmaceutical composition comprising a pre-formed dissolvablehydrogel can be administered to a target site (e.g., a wound) by directimplantation and surgery.

Embodiments of Various Aspects Described Herein can be Defined in any ofthe Following Numbered Paragraphs:

-   -   1. A method comprising:        -   (a) contacting a wound with a hydrogel composition            comprising a dissolvable hydrogel layer, wherein the            dissolvable hydrogel layer comprises linear, branched,            and/or dendritic crosslinkable polymers held together by            covalent bonds formed between the first crosslinkable            polymer and the second crosslinkable polymer, wherein the            dissolvable hydrogel layer comprises thioester linkages; and        -   (b) allowing the dissolvable hydrogel layer to adhere to            tissue surrounding the wound.    -   2. The method of paragraph 1, further comprising dissolving the        dissolvable hydrogel layer by adding a thiolate compound to        result in a thiol-thioester exchange, thereby releasing the        hydrogel composition from the wound.    -   3. A method comprising:        -   (a) contacting a wound with a hydrogel composition            comprising a dissolvable hydrogel layer, wherein the            dissolvable hydrogel layer comprises linear, branched,            and/or dendritic crosslinkable polymers held together by            thioester linkages formed between the first crosslinkable            polymer and the second crosslinkable polymer;        -   (b) allowing the dissolvable hydrogel layer to adhere to            tissue surrounding the wound; and        -   (c) dissolving the dissolvable hydrogel layer by adding a            thiolate compound to result in a thiol-thioester exchange,            thereby releasing the hydrogel composition from the wound.    -   4. The method of any of paragraphs 1-3, wherein the dissolvable        hydrogel layer is derived from a first water-soluble linear,        branched, and/or dendritic crosslinkable polymer comprising at        least two thiol moieties and a second water-soluble linear,        branched, and/or dendritic crosslinkable polymer comprising at        least two crosslinking moieties that are capable of reacting        with said at least two thiol moieties of the first crosslinkable        polymer to form the thioester linkages between the first and        second crosslinkable polymers.    -   5. The method of paragraph 1 or 2, wherein the dissolvable        hydrogel layer is derived from a first water-soluble linear,        branched, and/or dendritic crosslinkable polymer comprising at        least two thioester linkages and a second water-soluble linear,        branched, and/or dendritic crosslinkable polymer comprising at        least two crosslinking moieties that are capable of forming a        linkage with the first water-soluble linear, branched, and/or        dendritic polymer.    -   6. The method of paragraph 1 or 2, wherein the dissolvable        hydrogel layer is derived from a first water-soluble linear,        branched and/or dendritic crosslinkable polymer comprising at        least two nucleophilic moieties that are capable of forming a        linkage with at least two crosslinking moieties of the        second-water soluble linear, branched and/or dendritic polymer;        wherein at least one of the first and second water-soluble        linear, branched and/or dendritic crosslinkable polymers        comprises at least two thioester linkages.    -   7. The method of any of paragraphs 1-6, wherein the linear        crosslinkable polymer comprises polyesters, polyethers,        polyether-esters, polyglycerols, polyamino acids,        polyester-amines, polyurethanes, polycarbonates, polyamino        alcohols, thiols, amines, N-hydroxysuccinimide (NHS) moieties,        maleimide (MAL) moieties, or any combinations thereof.    -   8. The method of any of paragraphs 1-7, wherein the branched        crosslinkable polymer comprises polyesters, polyethers,        polyether-esters, polyglycerols, polyamino acids,        polyester-amines, polyurethanes, polycarbonates, polyamino        alcohols, thiols, amines, N-hydroxysuccinimide (NHS) moieties,        Maleimide (MAL) moieties, or any combinations thereof.    -   9. The method of any of paragraphs 1-8, wherein the dendritic        crosslinkable polymer comprises polyesters, polyethers,        polyether-esters, polyamino acids, polyester-amines,        polyurethanes, polycarbonates, polyamino alcohols, thiols,        amines, N-hydroxysuccinimide (NHS) moieties, Maleimide (MAL)        moieties, or any combinations thereof.    -   10. The method of any of paragraphs 1-9, wherein the first        crosslinkable polymer has a chemical structure selected from the        group consisting of structure (i)-structure (xii) shown as        follows:

and any combinations thereof; and wherein:

Q is independently selected from the group consisting of O, S, Se, NH,CH₂ and any combination thereof;

R is selected from the group consisting of a hydrogen, straight orbranched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and m, n, and x are eachindependently selected from an integer of 0-1000.

-   -   11. The method of any of paragraphs 4-10, wherein said at least        two crosslinking moieties comprise at least one        N-hydroxysuccinimide (NHS) or maleimide (MAL) moeity.    -   12. The method of any of paragraphs 4-10, wherein said at least        two crosslinking moieties comprise at least two        N-hydroxysuccinimide (NHS) or maleimide (MAL) moeities.    -   13. The method of any of paragraphs 1-12, wherein the second        cross-linkable polymer has a chemical structure selected from        the group consisting of structure (xiii)-structure (xl) shown us        follows:

and any combination thereof; and wherein

Q is independently selected from the group consisting of O, S, Se, NH,CH₂ and any combination thereof;

R is selected from the group consisting of a hydrogen, straight orbranched alkyl, cycloalkyl, aryl, olefin or alkyne, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and

m, n, x, y and z are each independently selected from an integer of0-1000.

-   -   14. The method of any of paragraphs 10-13, wherein R is selected        from the group consisting of poly(ethylene glycol),        poly(ethylene oxide), poly(hydroxyacid), a carbohydrate, a        protein, a polypeptide, an amino acid, a nucleic acid, a        nucleotide, a polynucleotide, a DNA segment, a RNA segment, a        lipid, a polysaccharide, an antibody, a pharmaceutical agent, an        epitope for a biological receptor, and any combinations thereof.    -   15. The method of any of paragraphs 1-14, wherein the thiolate        compound is selected from the group consisting of linear,        branched and/or dendritic multi-thiol macromolecule,        poly(ethylene glycol) thiol, thiol containing glycerol, thiol        containing peptide, cysteine, cystine, alkyl ester of cysteine,        alkyl ester of cystine, MeSCH₂SH,        (R)/(S)-3-methyl-3-sulfanylhexan-1-ol, Ethanethiol,        1-Propanethiol, 2-Propanethiol, Butanethiol, tert-Butyl        mercaptan, Pentanethiols, Thiophenol, Dimercaptosuccinic acid,        Thioacetic acid, 5-mercapto-4H-[1,2,4]triazol-3-ol,        2-mercaptoacetamide, 2-Mercaptoethanol, 1,2-Ethanedithiol,        Ammonium thioglycolate, Cysteamine, Methyl thioglycolate,        Thiolactic acid, 1-Mercapto-2-propanol, 2-methoxyethanethiol,        3-Mercapto-1-propanol, 2,3-Dimercapto-1-propanol,        1-Thioglycerol, Mercaptosuccinic acid,        4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol,        N-Carbamoyl-L-cysteine, 2-Methyl-3-sulfanylpropanoic acid,        4-mercaptobutyric acid, N-Acctyleysteamine,        3-Methyl-1-butanethiol, 1,5-Pentanedithiol, 4-Chlorothiophenol,        4-Aminothiophenol, Benzyl mercaptan, 2-Furanmethanethiol,        3-Mercaptohexanol, Furfuryl thiol, derivatives thereof, a        disulfide complex of one or more thereof, and any combinations        thereof.    -   16. The method of any of paragraphs 1-15, wherein the        dissolvable hydrogel layer is at least partially flexible.    -   17. The method of any of paragraphs 1-16, wherein the        dissolvable hydrogel layer is at least partially adhesive.    -   18. The method of any of paragraphs 1-17, wherein the        dissolvable hydrogel layer is capable of withstanding a pressure        of at least about 2 mmHg.    -   19. The method of any of paragraphs 1-18, wherein the        dissolvable hydrogel layer is transparent.    -   20. The method of any of paragraphs 1-19, wherein the        dissolvable hydrogel layer is hydrophilic.    -   21. The method of any of paragraphs 1-20, wherein the        dissolvable hydrogel layer is elastic or viscoelastic.    -   22. The method of any of paragraphs 1-21, wherein the        dissolvable hydrogel layer has about 5 wt % to about 70 wt % of        the crosslinkable polymers.    -   23. The method of any of paragraphs 1-22, wherein the hydrogel        composition further comprises a bioactive agent.    -   24. The method of paragraph 23, wherein the bioactive agent is        selected from the group consisting of pharmaceutical agents,        drugs, cells, gases and gaseous precursors, synthetic organic        molecules, proteins, enzymes, growth factors, vitamins, steroid,        polyanions, nucleosides, nucleotides, polynucleotides,        nanoparticles, diagnostic agents, genetic materials, and any        combinations thereof.    -   25. The method of any of paragraphs 1-24, wherein the hydrogel        composition is formulated to form a bandage, glue, sealant,        dressing, scaffold, coating, or covering.    -   26. The method of any of paragraphs 1-25, wherein the hydrogel        composition is used with vacuum assisted closure.    -   27. The method of any of paragraphs 1-26, wherein the thiolate        compound is formulated as a solution or a spray.    -   28. A dissolvable hydrogel composition comprising: an adhesive        hydrogel layer comprising a first water-soluble linear,        branched, and/or dendritic crosslinkable polymer and a second        water-soluble linear, branched, and/or dendritic crosslinkable        polymer held together by thioester linkages formed between the        first crosslinkable polymer and the second crosslinkable        polymer,        -   wherein the first crosslinkable polymer comprises at least            two thiol moieties and the second crosslinkable polymer            comprises at least two crosslinking moieties that are            capable of reacting with said at least two thiol moieties of            the first crosslinkable polymer to form the thioester            linkages between the first crosslinkable polymer and the            second crosslinkable polymer.    -   29. A dissolvable hydrogel composition comprising: an adhesive        hydrogel layer comprising a first water-soluble linear, branched        and/or dendritic crosslinkable polymer and a second        water-soluble linear, branched and/or dendritic crosslinkable        polymer held together by covalent bonds formed between the first        crosslinkable polymer and the second crosslinkable polymer,        wherein the adhesive hydrogel layer comprises thioester        linkages.    -   30. The dissolvable hydrogel composition of paragraph 29,        wherein the first crosslinkable polymer comprises at least two        thiol moieties and the second crosslinkable polymer comprises at        least two crosslinking moieties that are capable of reacting        with said at least two thiol moieties of the first crosslinkable        polymer to form the thioester linkages between the first        crosslinkable polymer and the second crosslinkable polymer;    -   31. The dissolvable hydrogel composition of paragraph 29,        wherein the first crosslinkable polymer comprises at least two        thioester linkages and the second crosslinkable polymer        comprises at least two crosslinking moieties that are capable of        forming a linkage with the first crosslinkable polymer.    -   32. The dissolvable hydrogel composition of paragraph 29,        wherein the first crosslinkable polymer comprises at least two        nucleophilic moieties that are capable of forming a linkage with        at least two crosslinking moieties of the second crosslinkable        polymer that comprises at least two thioester linkages.    -   33. The dissolvable hydrogel composition of any of paragraphs        28-32, wherein the linear crosslinkable polymer comprises        polyesters, polyethers, polyglycerols, polypeptides,        polyether-esters, polyamino acids, polyester-amines,        polyurethanes, polycarbonates, polyamino alcohols, thiols,        amines, N-hydroxysuccinimide (NHS) moieties, maleimide (MAL)        moieties, or any combinations thereof.    -   34. The dissolvable hydrogel composition of any of paragraphs        28-33, wherein the branched crosslinkable polymer comprises        polyesters, polyethers, polyglycerols, polypeptides,        polyether-esters, polyamino acids, polyester-amines,        polyurethanes, polycarbonates, polyamino alcohols, thiols,        amines, N-hydroxysuccinimide (NHS) moieties, maleimide (MAL)        moiety, or any combinations thereof.    -   35. The dissolvable hydrogel composition of any of paragraphs        28-34, wherein the dendritic crosslinkable polymer comprises        polyesters, polyethers, polyglycerols, polypeptides,        polyether-esters, polyamino acids, polyester-amines,        polyurethanes, polycarbonates, polyamino alcohols, thiols,        amines, N-hydroxysuccinimide (NHS) moieties, maleimide (MAL)        moieties, or any combinations thereof.    -   36. The dissolvable hydrogel composition of any of paragraphs        28-35, wherein when both the first and second crosslinkable        polymers are branched or dendritic crosslinkable polymers, at        least one of the first and the second dendritic crosslinkable        polymers does not comprise poly(ethylene glycol).    -   37. The dissolvable hydrogel composition of any of paragraphs        28-36, wherein the first crosslinkable polymer has a chemical        structure selected from the group consisting of structure (i) to        structure (xii) shown as follows:

and any combinations thereof; and wherein:

Q is independently selected from the group consisting of O, S, Se, NH,CH₂, and any combination thereof;

R is selected from the group consisting of a hydrogen, straight orbranched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; when at least two R groupsare in the same structure, R can be different from each other and

m, n, x, and y are each independently selected from an integer of0-1000.

-   -   38. The dissolvable hydrogel composition of any of paragraphs        28-37, wherein said at least two crosslinking moieties comprise        at least one N-hydroxysuccinimide (NHS) moiety or maleimide        (MAL) moiety.    -   39. The dissolvable hydrogel composition of any of paragraphs        28-38, wherein said at least two crosslinking moieties comprise        at least two N-hydroxysuccinimide (NHS) moieties or maleimide        (MAL) moieties.    -   40. The dissolvable hydrogel composition of any of paragraphs        28-39, wherein the second crosslinkable polymer has a chemical        structure selected from the group consisting of structure (xiii)        to structure (xl) shown as follows:

and any combination thereof; and wherein

Q is independently selected from the group consisting of O, S, Se, NH,CH₂, and any combination thereof;

R is selected from the group consisting of a hydrogen, straight orbranched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; when at least two R groupsare in the same structure, R can be different from each other and

m, n, x, y and z are each independently selected from an integer of0-1000.

-   -   41. The dissolvable hydrogel composition of any of paragraphs        37-40, wherein R is selected from the group consisting of        poly(ethylene glycol), poly(ethylene oxide), poly(hydroxyacid),        a carbohydrate, a protein, a polypeptide, an amino acid, a        nucleic acid, a nucleotide, a polynucleotide, a DNA segment, a        RNA segment, a lipid, a polysaccharide, an antibody, a        pharmaceutical agent, an epitope for a biological receptor, and        any combinations thereof.    -   42. The dissolvable hydrogel composition of any of paragraphs        28-41, wherein the first crosslinkable polymer has a chemical        structure as follows:

-   -   43. The dissolvable hydrogel composition of any of paragraphs        28-42, wherein the second crosslinkable polymer is poly(ethylene        glycol) disuccinimidyl valerate.    -   44. The dissolvable hydrogel composition of any of paragraphs        28-43, wherein the adhesive hydrogel layer is at least partially        flexible.    -   45. The dissolvable hydrogel composition of any of paragraphs        28-44, wherein the adhesive hydrogel layer is capable of        withstanding a pressure of at least about 2 mmHg.    -   46. The dissolvable hydrogel composition of any of paragraphs        28-45, wherein the adhesive hydrogel layer is transparent.    -   47. The dissolvable hydrogel composition of any of paragraphs        28-46, wherein the adhesive hydrogel layer is hydrophilic.    -   48. The dissolvable hydrogel composition of any of paragraphs        28-47, wherein the adhesive hydrogel layer is elastic or        viscoelastic.    -   49. The dissolvable hydrogel composition of any of paragraphs        28-48, wherein the adhesive hydrogel layer has about 5 wt % to        about 70 wt % of the crosslinkable polymers.    -   50. The dissolvable hydrogel composition of any of paragraphs        28-49, further comprising a bioactive agent.    -   51. The dissolvable hydrogel composition of paragraph 50,        wherein the bioactive agent is selected from the group        consisting of pharmaceutical agents, drugs, cells, gases and        gaseous precursors, synthetic organic molecules, proteins,        enzymes, growth factors, vitamins, steroids, polyanions,        nucleosides, nucleotides, polynucleotides, nanoparticles,        diagnostic agents, genetic materials, and any combinations        thereof.    -   52. The dissolvable hydrogel composition of any of paragraphs        28-51, wherein the adhesive layer is hydrolytically stable at pH        in a range of about 0 to at least about 9.    -   53. The dissolvable hydrogel composition of any of paragraphs        28-52, wherein the dissolvable hydrogel composition is        formulated to form a bandage, glue, sealant, dressing, scaffold,        coating, or covering.    -   54. The dissolvable hydrogel composition of any of paragraphs        28-53, wherein the dissolvable hydrogel composition is adapted        for use with vacuum assisted closure.    -   55. A kit comprising:        -   a dissolvable hydrogel composition comprising: an adhesive            hydrogel layer comprising linear, branched, and/or dendritic            crosslinkable polymers held together by thioester linkages            formed between the linear, branched, and/or dendritic            crosslinkable polymers; and        -   a thiolate compound.    -   56. A kit comprising:        -   a dissolvable hydrogel composition comprising: an adhesive            hydrogel layer comprising hum, branched and/or dendritic            crosslinkable polymers held together by covalent bonds            formed between the first crosslinkable polymer and the            second crosslinkable polymer, wherein the adhesive hydrogel            layer comprises thioester linkages; and        -   a thiolate compound.    -   57. The kit of paragraph 56, wherein the adhesive hydrogel layer        is derived from a first water-soluble linear, branched, and/or        dendritic crosslinkable polymer comprising at least two thiol        moieties and a second water-soluble linear, branched, and/or        dendritic crosslinkable comprising at least two crosslinking        moieties that are capable of reacting with said at least two        thiol moieties of the first crosslinkable polymer to form the        thioester linkages between the first and the second        crosslinkable polymers.    -   58. The kit of paragraph 56, wherein the adhesive hydrogel layer        is derived from a first water-soluble linear, branched, and/or        dendritic crosslinkable polymer comprising at least two        thioester linkages and a second water-soluble linear, branched,        and/or dendritic crosslinkable polymer comprising at least two        crosslinking moieties that are capable of forming a linkage with        the first water-soluble linear, branched, and/or dendritic        polymer.    -   59. The kit of paragraph 56, wherein the adhesive hydrogel layer        is derived from a first water-soluble linear, branched and/or        dendritic crosslinkable polymer comprising at least two        nucleophilic moieties that are capable of forming a linkage with        the second water-soluble linear, branched and/or dendritic        polymer, wherein at least one of the first and second        water-soluble linear, branched and/or dendritic crosslinkable        polymers comprises at least two thioester linkages.    -   60. The kit of any of paragraphs 55-59, wherein the adhesive        hydrogel layer is hydrolytically stable at pH in a range of        about 0 to at least about 9.    -   61. The kit of any of paragraphs 55-60, wherein the adhesive        hydrogel layer has a larger molecular weight than the        crosslinkable polymers.    -   62. The kit of any of paragraphs 55-61, wherein the adhesive        hydrogel layer has a molecular weight of at least about 100 kDa.    -   63. The kit of any of paragraphs 55-62, wherein the dissolvable        hydrogel composition is formulated to form a bandage, sealant,        coating or covering.    -   64. The kit of any of paragraphs 55-63, further comprising at        least one component for performing vacuum assisted closure.    -   65. The kit of any of paragraphs 55-64, wherein the dissolvable        hydrogel composition further comprises a bioactive agent.    -   66. A kit comprising:        -   a first water-soluble linear, branched, and/or dendritic            crosslinkable polymer comprising at least two thiol            moieties, wherein the first crosslinkable polymer is at            least about 200 Da;        -   a second water-soluble linear, branched, and/or dendritic            crosslinkable polymer that can react with the first            crosslinkable polymer to form a dissolvable and adhesive            hydrogel, wherein the second crosslinkable polymer comprises            at least two crosslinking moieties that are capable of            reacting with the thiol moieties of the first crosslinkable            polymer to form thioester linkages between the first and the            second crosslinkable polymers; and wherein the second            crosslinkable polymer is at least about 200 Da; and        -   a thiolate compound.    -   67. A kit comprising:        -   a first water-soluble linear, branched, and/or dendritic            crosslinkable polymer comprising at least two thioester            linkages, wherein the first crosslinkable polymer is at            least about 200 Da;        -   a second water-soluble linear, branched, and/or dendritic            crosslinkable polymer that can react with the first            crosslinkable polymer to form a dissolvable and adhesive            hydrogel, wherein the second crosslinkable polymer comprises            at least two crosslinking moieties that are capable of            forming a linkage with the first crosslinkable polymer; and            wherein the second crosslinkable polymer is at least about            200 Da; and        -   a thiolate compound.    -   68. A kit comprising:        -   a first water-soluble linear, branched and/or dendritic            crosslinkable polymer that can react with the second            crosslinkable polymer to form a dissolvable and adhesive            thioester hydrogel, wherein the first crosslinkable polymer            comprises at least two nucleophilic moieties that are            capable of forming a linkage with the second crosslinkable            polymer; and wherein the first crosslinkable polymer is at            least about 200 Da;        -   a second water-soluble linear, branched and/or dendritic            crosslinkable polymer comprising at least two thioester            linkages, wherein the second crosslinkable polymer is at            least about 200 Da; and        -   a thiolate compound.    -   69. The kit of any of paragraphs 55-68, wherein the first        crosslinkable polymer, the second crosslinkable polymer, and the        thiolate compound are each independently formulated in a form        selected from the group consisting of a spray, a foam, a        solution, a powder, and any combinations thereof.    -   70. The kit of any of paragraphs 55-69, further comprising a        bioactive agent.    -   71. The kit of paragraph 70, wherein the bioactive agent is        selected from the group consisting of pharmaceutical agents,        drugs, cells, gases and gaseous precursors, synthetic organic        molecules, proteins, enzymes, growth factors, vitamins,        steroids, polyanions, nucleosides, nucleotides, polynucleotides,        nanoparticles, diagnostic agents, genetic materials, and any        combinations thereof.    -   72. The kit of any of paragraphs 55-71, wherein the thiolate        compound is provided in an amount such that the stoichiometric        ratio of the number of thiols in the thiolate compound to the        number of thioester linkages in the dissolvable hydrogel is        greater than 1:1.    -   73. The kit of any of paragraphs 55-72, wherein the first        crosslinkable polymer has a chemical structure selected from the        group consisting of structure (i) to structure (xii) shown as        follows:

and any combinations thereof; and wherein:

Q is independently selected from the group consisting of O, S, Se, NH,CH₂ and any combination thereof;

R is selected from the group consisting of a hydrogen, straight orbranched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and

m, n, x, and y are each independently selected from an integer of0-1000.

-   -   74. The kit of any of paragraphs 55-73, wherein said at least        two crosslinking moieties of the second crosslinkable polymer        comprises at least one N-hydroxysuccinimide (NHS) moiety or        maleimide (MAL) moiety.    -   75. The kit of any of paragraphs 55-74, wherein said at least        two crosslinking moieties of the second crosslinkable polymer        comprises at least two N-hydroxysuccinimide (NHS) moieties or        maleimide (MAL) moieties.    -   76. The kit of any of paragraphs 55-75, wherein the second        crosslinkable polymer has a chemical structure selected from the        group consisting of structure (xiii) to structure (xl) shown as        follows:

and any combination thereof; and wherein

Q is independently selected from the group consisting of O, S, Se, NH,CH₂ and any combination thereof;

R is selected from the group consisting of a hydrogen, straight orbranched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and

m, n, x, y, and z are each independently selected from an integer of0-1000.

-   -   77. The kit of any of paragraphs 73-76, wherein R is selected        from the group consisting of poly(ethylene glycol),        poly(ethylene oxide), poly(hydroxyacid), a carbohydrate, a        protein, a polypeptide, an amino acid, a nucleic acid, a        nucleotide, a polynucleotide, a DNA segment, a RNA segment, a        lipid, a polysaccharide, an antibody, a pharmaceutical agent, an        epitope for a biological receptor, and any combinations thereof.    -   78. The kit of any of paragraphs 55-77, wherein the first        crosslinkable polymer has a chemical structure as follows:

-   -   79. The kit of any of paragraphs 55-78, wherein the first        crosslinkable polymer has a chemical structure as follows:

-   -   80. The kit of any of paragraphs 55-79, wherein the second        crosslinkable polymer is poly(ethylene glycol) disuccinimidyl        valerate.    -   81. The kit of any of paragraphs 55-80, wherein the thiolate        compound is selected from the group consisting of linear,        branched and/or dendritic multi-thiol macromolecules,        poly(ethylene glycol) thiol, thiol-containing glycerol,        thiol-containing peptides, cysteine, cystine, alkyl ester of        cysteine, alkyl ester of cystine, MeSCH₂SH,        (R)/(S)-3-methyl-3-sulfanylhexan-1-ol, Ethanethiol,        1-Propanethiol, 2-Propanethiol, Butanethiol, tert-Butyl        mercaptan, Pentanethiols, Thiophenol, Dimercaptosuccinic acid,        Thioacetic acid, 5-mercapto-4H-[1,2,4]triazol-3-ol,        2-mercaptoacetamide, 2-Mercaptoethanol, 1,2-Ethanedithiol,        Ammonium thioglycolate, Cysteamine, Methyl thioglycolate,        Thiolactic acid, 1-Mercapto-2-propanol, 2-methoxyethanethiol,        3-Mercapto-1-propanol, 2,3-Dimercapto-1-propanol,        1-Thioglycerol, Mercaptosuccinic acid,        4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol,        N-Carbamoyl-L-cysteine, 2-Methyl-3-sulfanylpropanoic acid,        4-mercaptobutyric acid, N-Acetylcysteamine,        3-Methyl-1-butanethiol, 1,5-Pentanedithiol, 4-Chlorothiophenol,        4-Aminothiophenol, Benzyl mercaptan, 2-Furanmethanethiol,        3-Mercaptohexanol, Furfuryl thiol, derivatives thereof, a        disulfide complex of one or more thereof.    -   82. The kit of any of paragraphs 55-81, wherein the adhesive        hydrogel layer is at least partially flexible.    -   83. The kit of any of paragraphs 55-82, wherein the adhesive        hydrogel layer is capable of withstanding a pressure of at least        about 2 mmHg.    -   84. The kit of any of paragraphs 55-83, wherein the adhesive        hydrogel layer is transparent.    -   85. The kit of any of paragraphs 55-84, wherein the adhesive        hydrogel layer is hydrophilic.    -   86. The kit of any of paragraphs 55-85, wherein the adhesive        hydrogel layer is elastic or viscoelastic.    -   87. The kit of any of paragraphs 55-86, wherein the adhesive        hydrogel layer has about 5 wt % to about 70 wt % of the        crosslinkable polymers.    -   88. A kit of any of paragraphs 55-87 for treatment of a wound in        a tissue of a subject.    -   89. The kit of paragraph 88, wherein the tissue is selected from        the group consisting of skin, heart, blood vessel, liver,        urinary tract, lung, gastrointestinal tract, stomach, joint,        bone, brain, car, alveolar bone, lymphatic tissue, buccal        tissue, and any combinations thereof.

SOME SELECTED DEFINITIONS OF TERMS

As used herein, a “subject” means a human or animal. Usually the animalis a vertebrate such as a primate, rodent, domestic animal or gameanimal. Primates include chimpanzees, cynomologous monkeys, spidermonkeys, and macaques, e.g., Rhesus. Rodents include mice, rats,woodchucks, ferrets, rabbits and hamsters. Domestic and game animalsinclude cows, horses, pigs, deer, bison, buffalo, feline species, e.g.,domestic cat, canine species, e.g., dog, fox, wolf, avian species, e.g.,chicken, emu, ostrich, and fish, e.g., trout, catfish and salmon. Incertain embodiments of the aspects described herein, the subject is amammal, e.g., a primate, e.g., a human. A subject can be male or female.Preferably, the subject is a mammal. The mammal can be a human,non-human primate, mouse, rat, dog, cat, horse, or cow, but are notlimited to these examples. Mammals other than humans can beadvantageously used as subjects that represent animal models of tissuerepair, regeneration and/or reconstruction. In addition, the methods andcompositions described herein can be used to treat domesticated animalsand/or pets.

As used herein, the terms “treating” or “treatment” encompass either orboth responsive and prophylaxis measures, e.g., designed to inhibit,slow, or delay the onset of a symptom of a disease or disorder, achievea full or partial reduction of a symptom or disease state, and/or toalleviate, ameliorate, lessen, or cure a disease or disorder and/or itssymptoms. As used herein, amelioration of the symptoms of a particulardisorder by administration of a particular compound or pharmaceuticalcomposition refers to any lessening of severity, delay in onset, slowingof progression, or shortening of duration, whether permanent ortemporary, lasting or transient that can be attributed to or associatedwith administration of the compound or composition.

The term “statistically significant” or “significantly” refers tostatistical significance and generally means a two standard deviation(2SD) below or above a reference level. The term refers to statisticalevidence that there is a difference. It is defined as the probability ofmaking a decision to reject the null hypothesis when the null hypothesisis actually true. The decision is often made using the p-value.

As used herein, the term “substantially” means a proportion of at leastabout 60%, or preferably at least about 70% or at least about 80%, or atleast about 90%, at least about 95%, at least about 97% or at leastabout 99% or more, or any integer between 70% and 100%. In someembodiments, the term “substantially” means a proportion of at leastabout 90%, at least about 95%, at least about 98%, at least about 99% ormore, or any integer between 90% and 100%. In some embodiments, the term“substantially” can include 100%.

As used herein, the term “comprising” means that other elements can alsobe present in addition to the defined elements presented. The use of“comprising” indicates inclusion rather than limitation.

The term “consisting of” refers to the components thereof as describedherein, which are exclusive of any element not recited in thatdescription of the embodiment.

As used herein the term “consisting essentially of” refers to thoseelements required for a given embodiment. The term permits the presenceof elements that do not materially affect the basic and novel orfunctional characteristic(s) of that embodiment of the invention

Other than in the operating examples, or where otherwise indicated, allnumbers expressing quantities of ingredients or reaction conditions usedherein should be understood as modified in all instances by the term“about.” The term “about” when used in connection with percentages maymean±5%.

The singular terms “a,” “an,” and “the” include plural referents unlesscontext clearly indicates otherwise. Similarly, the word “or” isintended to include “and” unless the context clearly indicatesotherwise. Although methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of thisdisclosure, suitable methods and materials are described below. Theabbreviation, “e.g.” is derived from the Latin exempli gratia, and isused herein to indicate a non-limiting example. Thus, the abbreviation“e.g.” is synonymous with the term “for example.” Furthermore, use ofthe term “including” as well as other forms, such as “includes,” and“included,” is not limiting.

Unless otherwise explained, all technical and scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which this disclosure belongs. Definitions of commonterms in diseases and disorders, separation and detection techniques canbe found in The Merck Manual of Diagnosis and Therapy, 18th Edition,published by Merck Research Laboratories, 2006 (ISBN 0-911910-18-2);Robert S. Porter et al. (eds.), The Encyclopedia of Molecular Biology,published by Blackwell Science Ltd., 1994 (ISBN 0-632-02182-9); andRobert A. Meyers (ed.), Molecular Biology and Biotechnology: aComprehensive Desk Reference, published by VCH Publishers, Inc., 1995(ISBN 1-56081-569-8).

As used herein, the abbreviations for any protective groups, aminoacids, and other compounds are, unless indicated otherwise, in accordwith their common usage, recognized abbreviations, or the IUPAC-IUBCommission on Biochemical Nomenclature, Biochem., 11:942-944 (1972).

It should be understood that this invention is not limited to theparticular methodology, protocols, and reagents, etc., described hereinand as such may vary. The terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to limit thescope of the present invention, which is defined solely by the claims.

All patents and other publications identified throughout thespecification are expressly incorporated herein by reference for thepurpose of describing and disclosing, for example, the methodologiesdescribed in such publications that might be used in connection with thepresent invention. These publications are provided solely for theirdisclosure prior to the filing date of the present application. Nothingin this regard should be construed as an admission that the inventorsare not entitled to antedate such disclosure by virtue of priorinvention or for any other reason. All statements as to the date orrepresentation as to the contents of these documents are based on theinformation available to the applicants and do not constitute anyadmission as to the correctness of the dates or contents of thesedocuments.

Some embodiments described herein are further illustrated by thefollowing example which should not be construed as limiting.

The contents of all references cited throughout this application,examples, as well as the figures and tables are incorporated herein byreference in their entirety.

EXAMPLES Example 1 An Exemplary Dissolvable Dendritic Thioester HydrogelBased on Thiol-Thioester Exchange and Characterizations Thereof

Reactions readily occurring in water are appealing for their potentialuse in biological and biomedical applications. For example,thiol-thioester exchange, the reaction between a thioester-containingsmall molecule and a thiolate anion to produce a new thioester andthiolate as products, proceeds in high yield in water, in solutions ofpH relevant to biological processes, and at room temperature. See, e.g.,Bracher, P. J., et al. Orig Life Evol Biosph 2011, 41, 399-4121. Whilecommon in biological processes and in native chemical ligation,thiol-thioester exchange has not been reported for use in organicsynthesis or in the construction of reversible molecular assemblies ormacromolecules such as hydrogel compositions. U. Yasuyuki, et al.,Science 2009, 325, 73-77; and U. Yasuyuki, et al., Org. Biomol. Chem.2009, 7, 2878-2884.

To this end, a strategy based on thiol-thioester exchange (a reversiblecovalent reaction) in a dendritic thioester hydrogel was evaluated. Theuse of the dendritic thioester hydrogel to close an ex vivo jugular veinpuncture and its controlled dissolution for gradual wound re-exposurebased on thiol-thioester exchanged were also presented herein. Whilehydrogels based on a thiol-disulfide interchange or native chemicalligation (NCL) are known (e.g., Hu, B.-H. et al, Biomacromolecules 2009,10, 2194-2200; Anumolu, S. S. et al., Biomaterials 2011, 32, 1204-1217),presented herein is the first example of hydrogel disassembly based onthiol-thioester exchange (FIG. 1B). A dendritic macromomer, for example,as described in Ghobril, C. et al. Angewendte Chemic InternationalEdition, 2013, 52, 14070-14074, was selected to synthesize a covalentlycrosslinked dendritic thioester hydrogel since the composition,structure and molecular weight can be precisely controlled to provide amacromer with multiple reactive sites to ensure rapid formation of ahydrogel.

As the hydrogel dissolution relies on thiol-thioester exchange, athioester-linked hydrogel as well as a control amide-linked hydrogelwere prepared. Specifically, a lysine-based peptide dendron 1 or 2possessing four terminal thiols or amines, respectively, was synthesizedin high yield (FIG. 2). First, the Cbz-protected G1 lysine (peptidedendron 4 indicated in FIG. 2) was synthesized following a previouslyreported procedure as described herein Wathier, M. et al., ChemMedChem2006, 1, 821-825. A poly(ethylene glycol) amine of 2000 Mw was thenintroduced on the peptide dendron by a classic peptide coupling reactionto enhance aqueous solubility, followed by the catalytic hydrogenolysisof the Cbz groups to generate dendron 2. Dendron 1 was prepared bycoupling the activated PFP-3-(tritylthio)propionic acid to dendron 2,followed by removal of tin, trityl groups using TFA and triethylsilanein DCM. The dendrons were characterized, e.g., by nuclear magneticresonance (NMR), matrix-assisted laser desorption/ionization (MALDI)and/or infra-red (IR) spectroscopy. Syntheses of dendrons 1 and 2 arefurther described in detail as follows:

Synthesis of Dendron 2.

HOBt (4.4 mmol) and EDCI (4.4 mmol) were added to a solution of 4 shownin FIG. 2 (4 mmol) in DMF (40 mL) at room temperature and undernitrogen. Next, a solution of MPEG2000-NH₂ (4 mmol) and DIPEA (4.8 mmol)in DMF (20 mL) was added dropwise. The reaction mixture was stirred atroom temperature overnight. The solvent was removed under vacuum, andthe crude product mixture was redissolved in CH₂Cl₂. The organic phasewas extracted with an aqueous sodium bicarbonate solution, water, andbrine to yield the Cbz-protected dendron. This compound was thendissolved in methanol (200 mL), and Pd/C (10%) was added. Next, thereaction was stirred under hydrogen for 48 hrs. The solution was thenfiltered through celite, washed several times with methanol, andconcentrated under vacuum. The transparent oil was triturated with etheruntil a precipitate formed. The solid was filtered and dried undervacuum to afford dendron 2 as a white solid (90%), which was used in thenext step without further purification. ¹H NMR (500 MHz, D₂O):δ=1.36-1.99 (m, 18H), 2.92 (m, 4H), 3.20 (m, 2H), 3.36-3.85 (m, ca.180H), 3.38 (s, 3H), 4.15 (m, 1H), 4.24 (m, 1H) ppm; MALDI-TOF-MS(positive ion) [M+Na⁺]: 2334; IR (neat): 3280, 2883, 1634, 1466, 1343,1105, 963, 842 cm⁻¹.

Synthesis of Dendron 1.

Et₃SiH (3.75 mmol) and TFA (2 mL) were added to a solution of 5 shown inFIG. 2 (0.25 mmol) in CH₂Cl₂ (5 mL). The solution was stirred at roomtemperature for 3 hrs. The solvent and TFA were removed under vacuum,and the product was triturated in ether until a precipitate formed. Thesolid was filtered, washed several times with ether, and dried undervacuum. A solution of HCl (1 N) was added, and the aqueous phase wasfiltered and lyophilized. Water was then added, and the pH adjusted to7. The aqueous phase was lyophilized again to afford dendron 1 as awhite solid (95%). The last step was conducted quickly to avoidoxidation of the thiols in water. ¹H NMR (500 MHz, D₂O): δ=1.37-1.77 (m,12H), 1.82 (m, 6H), 2.57-2.70 (m, 8H), 2.80 (m, 8H), 3.24 (m, 6H), 3.42(s, 3H), 3.50-3.74 (m, ca. 180H), 4.28-4.33 (m, 3H) ppm; ¹³C NMR (100MHz, D₂O): δ−174.2, 173.8, 173.7, 71.1 −66.6 (OCH₂CH₂), 58.5, 58.2,54.4, 54.1, 40.2, 39.8, 39.5, 39.1, 30.8, 28.2, 22.8, 20.9, 20.4, 19.9ppm; MALDI-TOF (positive ion) [M+Na⁺]: 2687; IR (neat): 3300, 3056,2869, 2553, 1653, 1558, 1457, 1348, 1096, 949, 843 cm⁻¹.

To prepare the hydrogels, a solution of dendron 1 or 2 in borate buffer(e.g., at pH ˜9) was reacted with a solution of poly(ethylene glycoldisuccinimidyl valerate.) of 3400 Mw (macromolecule 3 indicated in FIG.1B: SVA-PEU-SVA) in PBS buffer at pH ˜6.5. The ratio of amine or thiolto SVA was about 1:1, and the total concentration of polymer in solutionwas either 10 wt % or 30 wt %. A hydrophilic gel formed spontaneouslywithin seconds upon mixing the two aqueous solutions at eitherconcentration. The gels exhibited viscoelastic properties and weretransparent. Cylindrical hydrogel samples of 9-mm diameter and 3-mmthickness were prepared and analyzed after keeping at ˜25° C. for about2 hrs. The mechanical strength and viscoelastic properties of thehydrogels were investigated using rheological measurements. First, thestrain sweep test was performed on both hydrogels, at a frequency ofabout 1 Hz, in order to establish the range of linear viscoelasticity(LVE). Then, the frequency sweep at a constant oscillatory stress of ˜50Pa was determined for all hydrogels before and after swelling (FIG. 3).PEG-LysSH and PEG-LysNH₂ hydrogels at either concentration showed strongelastic properties with low tan δ(<5° and exhibited a storage modulus G′greater than a loss modulus G″ at frequencies between 0.1 and 10 Hz.Before swelling, G′ values for 30 wt % PEG-LysSH (reversible) andPEG-LysNH₂ (non-reversible) hydrogels were about 37×10³ and 14×10³ Pa,respectively, at 1 Hz frequency (FIG. 3). The increase in modulus isalso consistent with the increase in the wt % of the polymer, about37×10³ Pa (30 wt %) vs. 6×10³ Pa (10 wt %) of PEG-LysSH hydrogel, at 1Hz frequency.

After exposure to 5 ml PBS buffer at pH ˜7.4, ˜30 wt % PEG-LysSH andPEG-LysNH₂ hydrogels swelled up to 400 and 600%, respectively, andreached equilibrium after 48 hrs (data not shown). The G′ values, atswelling equilibrium, decreased by approximately half, for bothhydrogels (FIG. 3). Hydrogels at a concentration of 10 wt %, G′ alsodecreased in a similar manner after 48 hours of exposure to PBS buffer,with the PEG-LysSH hydrogel possessing the lowest G′ value (ca. 200 Pa)at a frequency of 1 Hz.

Without wishing to be bound by theory, in a competing process,thioesters can spontaneously hydrolyze in water to form carboxylicacids, which could prevent the formation of the gel. In the conditionsdescribed in this Example, PEG-LysSH hydrogels were formed withinseconds and were stable to hydrolysis for several days. The rheologicaldata show that both hydrogels exhibited suitable mechanical propertiesas evident by higher G′ values, even after swelling for 48 hrs (exceptfor 10 wt % PEG-LysSH). These results indicate that these hydrogels canbe used as hemostats for treatment of wounds, as even after absorbing ofwater, they still maintain their integrity, which should prolong theircontact time on skin and prevent structural breakage.

Next, the reversibility or dissolution capability of the 30 wt %PEG-LysSH and PEG-LysNH₂ based hydrogels were evaluated to determine ifa thiol-thioester exchange between the thioester bonds in the hydrogeland a thiolate in aqueous solution (e.g., but not limited to cysteine)would dissolve the hydrogel and form an amide linkage to preventhydrogel re-formation (FIG. 4). Three solutions that contained differentnucleophiles were evaluated; these contained (1) l-cysteine methyl ester(CME; reacts by an NCL-based mechanism); (2) the water-soluble thiolate2-mercaptoethanesultbnate (MES); and (3) l-lysine methyl ester (LME; theamine acts as the nucleophile). Under all three conditions, thedissolution of the hydrogel was evaluated at equilibrium after swellingin PBS buffer at pH 7.4. The PEG-LysNH₂ hydrogel that contains the amidebonds was used as a control system. It was observed that the pH of thebuffer solution and the concentration of the thiolate solution had asignificant impact on the rate of exchange, and thus on the dissolutiontime of the thioester hydrogel. Increasing the concentration of the CMEsolution to 0.5 Mat a constant pH of 7.4 led to a decrease in thedissolution time of the hydrogel from t_(1/2)=30 min to t_(1/2)=18 min(FIG. 4 (5)). Similarly, when the pH was increased to 8.5 at a constantconcentration of the CME solution (0.3 M), the thioester bridges in thegel were rapidly cleaved, and the hydrogel completely dissolved witht_(1/2)=12 min (t_(1/2)=25 min at pH 7.4; FIG. 4 (6)). Upon exposure ofthe PEG-LysSH hydrogel to an excess of MES solution (0.3 M) in PBS at pH8.5, the dissolution time of the gel (t_(1/2)=10 min) was comparable tothat in CME solution. Interestingly, an LME solution (0.3 M) in PBS atpH 8.5 did not cleave the thioester bridges of the PEG-LysSH hydrogeleven after 60 min, which demonstrates that a thiol-thioester exchange isresponsible for the dissolution of the hydrogel in the presence of CME.As expected, when the PEG-LysNH₂ hydrogel was exposed to CME solution(0.3 M) at pH 8.5, the gel did not dissolve, even after one hour ofexposure (FIG. 4, (2)).

Example 2 Assessment of an Exemplary Dissolvable Dendritic ThioesterHydrogel for Use in Hemostasis of a Wound

In order to evaluate the PEG-LysSH hydrogel for hemostasis of wound, itsadherence to ex vivo human skin tissues was first assessed. A solutionof ˜30 wt % PEG-LysSH hydrogel solution (or 30 wt % of PEG-LysNH₂hydrogel as a control) in borate buffer was mixed with a solution ofSVA-PEG-SVA (indicated as macromolecule 3 in FIG. 1B) in PBS and appliedto the ex vivo human skin. The gel formed within seconds and reachedequilibrium after 1 hr. As shown in FIGS. 5A-5B, torsional stress wasapplied on both PEG-LysSH (FIG. 5A) and PEG-LysNH₂ (FIG. 5B) hydrogelsto assess their adherence strength and flexibility on the skin. Upon theapplication of the torsional stress, both gels remained intact. Next,the dissolution of the thioester-crosslinked hydrogel upon exposure to˜0.3 M CME in PBS buffer, at pH ˜8.5 was evaluated. As shown in FIG. 5C,after ˜30 mins, the PEG-LysSH hydrogel was completely dissolved andwashed off while PEG-LysNH₂ only swelled and was still adhered on theskin even after several hrs.

An in vitro cytotoxicity study with the PEG-LysSH hydrogel (30 wt %) wasperformed with NIH3T3 murine fibroblast cells. The viability of thecells was 97±3% after exposure to the hydrogel for 24 hours and similarto that of the untreated control (p>0.05). The cytotoxicity of CMEbuffer solutions (0.1 M and 0.3 M) at pH 7.4 and 8.5 in the presence ofthe thioester hydrogel was also assessed. The cells were completelyviable after exposure to the cysteine buffer solutions for one hour ateither pII or concentration.

An in vitro macrophage activation study was performed with PEG-LysSH todetermine whether the hydrogel induces an immune response. Macrophageswere exposed to the PEG-LysSH hydrogel (30 wt %) for 24 hours (n=3), orlipopolysaccharide (LPS; 1 mgmL⁻¹), a component of Gram-negativebacteria that elicits an immune response as the positive control. Mediasamples were then tested for IL-6, a marker of macrophage activation.LPS exposure afforded a statistically higher IL6 response than thehydrogel (p<0.01); the response to the hydrogel was statisticallyindistinguishable (p>0.05) to that of a media only control. ThePEG-LysSH hydrogel (30 wt %) does not activate macrophages withconcomitant production of IL-6.

The PEG-LysSH hydrogel was also evaluated as a sealant on an ex vivojugular vein, in order to simulate a trauma caused by bleeding. As shownin FIGS. 6A-6B, the jugular vein was first linked to a syringe pump andfilled with PBS solution. Prior to the application of the gel, thepressure was increased in the vein to ensure that the system isleak-proof and that it could withstand pressures of ca. 250 mmHg (theupper limit of detection; n=3), which is significantly greater thannormal arterial blood pressure (120 mmHg). Next, a 2.5 mm hole was madeon the vein surface, and the pressure dropped to zero (FIG. 6C). Dendron1 and SVA-PEG-SVA 3 (as shown in FIG. 1B) were quickly mixed at roomtemperature, and a solution of 100 μL (30 wt %) was applied to thepuncture site (FIG. 6D). Within 5 min of closing the incision, thehydrogel sealant secured the wound without leakage as the syringe pumpcontinuously increased the pressure to approximately 250 mmHg (n=3) (Asa comparison, normal arterial blood pressure is typically around 120/80mmHg). Application of CME afforded dissolution of the sealant, and thewound leaked again. The procedure with the hydrogel sealant was facileto carry out and did not inflict additional tissue trauma.

Presented herein relates to synthesis of one or more embodiments of adendritic thioester hydrogel, which can gel within seconds from multiplethioester linkages formed between the thiol residues of dendron 1 andthe poly(ethylene glycol) macromer, e.g., SVA-PEG-SVA (macromolecule 3).In some embodiments, the thioester gel can exhibit strong mechanicalproperties even after swelling in PBS buffer, as shown by the highstorage modulus G′ value and can adhere to human skin tissue even whentorsional stress was applied. The thioester hydrogel can be completelydissolved and/or washed off upon exposure to a thiolate solution basedon the thiol-thioester exchange mechanism. While thiol-thioesterexchange process occurs between small molecules and/or protein fragmentsin biological processes, it has not been yet explored in macromolecularassemblies such as hydrogels. The use of a reversible thioester hydrogelbased on the thiol-thioester exchange mechanism can be versatile, e.g.,for hemostasis of wounds as opposed to commercially available wounddressings that typically require mechanical debridement and/or surgicalexcision of removal of the dressings or clotting agent. For example, thenovel capability of controlled dissolution of a thioester hydrogeldescribed herein can allow for gradual wound re-exposure in a surgicaltheatre setting for definitive surgical care, e.g., without inflictingany unnecessary tissue trauma or damage.

Example 3 Stability of an Exemplary Dissolvable Dendritic ThioesterHydrogel

The hydrolysis of alkyl thioesters is thermodynamically favorable toform a thiol and carboxylic acid, and it is generally believed thatthioesters are not stable in aqueous solution. Specifically, in smallmolecules this hydrolysis rate is pH dependent. Thioester hydrolysis hasbeen previously reported in the context of the origins of life thatsmall molecule thioesters such as CH₃C(O)SCH₃ (with a molecule weight ofabout 90 Da or 90 g/mol) hydrolyze 10,000 times faster at high pH (e.g.,above pH ˜7) and low pH (e.g., below pH ˜3) and are relatively stable atpH ˜3 to ˜7.

However, the hydrolysis of alkyl thioesters present in crosslinkedpolymer systems such as crosslinked hydrogels which have high watercontent has not yet been studied. Surprisingly, in accordance withvarious embodiments described herein, a thioester crosslinked hydrogelformed between thiol and an activated ester is stable at pH from 0 toabout 9 (FIG. 7). Without wishing to be bound by theory, this increasein stability can be, at least in part, a result of the polymer chainbackbone stabilizing the thioester bond since hydrolysis would requirethe polymer chain to change conformation or rearrange in space. As thechains are generally confined to an area via the crosslinked hydrogel, aconformational change or rearrangement of polymer chains can become lessfavorable.

Thiol-thioester exchange in water, where a thiol replaces a thiol in athioester, is known to occur readily in solution with small molecules.For example, adding an equivalent number of free thiols to a solution ofthioester small molecules (e.g., thiol: thioester stoichiometric ratiois about 1:1) is sufficient to lead to thiol-thioester exchange. Incontrast, thioester crosslinked hydrogels are unexpectedly stable. Asshown in FIG. 7, when the equivalent number of thiols added to athioester hydrogel was four (based on the number thioester linkages),there was almost no change in mechanical properties over a period of atleast about 60 minutes. Thiol-thioester exchange reactions appeared tooccur very slowly or insignificantly. Thus, adding an equivalent numberof free thiols to a thioester crosslinked hydrogel is not sufficient toallow significant thiol-thioester exchange to occur. Instead, thethioester crosslinked hydrogel can be dissolved upon addition of anexcess of free thiols (e.g., as shown in FIG. 4). These combined dataindicate that the thioester exchange reaction in a thioester crosslinkedhydrogel is generally slow and unfavorable unless an excess of freethiols is used. Without wishing to be bound by theory, as the polymerchains are generally confined to an area via the crosslinked hydrogel, aconformational change or rearrangement of polymer chains can become lessfavorable.

Example 4 Comparison of an Exemplary Thioester Crosslinked Hydrogel to aS—S Crosslinked Hydrogel

The stability and reactivity of thioester-crosslinked hydrogels is instark contrast to S—S crosslinked hydrogels. The S—S bond is previouslyknown to cleave under reducing conditions and when the S—S bond isincorporated into a hydrogel, the same reducing conditions can cleavethe bond and degrade the hydrogel. However, as discussed above, thethioester bonds incorporated into a crosslinked hydrogel appear to bemore stable during a thioester exchange reaction unless an excess offree thiols is used.

Further, on a weight basis of polymer added, the S—S crosslinkedhydrogels (8-arm-PEG-SH (20 kDa), Sinko, P. J. et al. Biomaterials 2011,32, 1204-1217) are generally weak relative to the thioester-crosslinkeddendritic hydrogels. For example, a ˜10 wt % S—S hydrogel has a storagemodulus G′ of about 3000 Pa (as compared to 6000 Pa for a ˜10 wt %thioester dendritic hydrogel as shown in FIG. 3) and is thus limited inits ability to seal a wound. In addition, the preparation of S—Scrosslinked pegylated hydrogels of greater wt % or with small macromersforming more S—S linkages per volume requires a significant amount ofH₂O₂ solution in water—more than what is available in the market—45%H₂O₂ or the use of large volumes of added H₂O₂ further reducing theoverall wt % of the final hydrogel solution. Thus, there is a practicallimitation in making S—S pegylated hydrogels of higher weight percents(e.g., ˜50% or higher) or smaller volumes. However, the thioestercrosslinked hydrogels have no such limitation and can be made at highweight percents as well as at small volumes.

Example 5 Use of an Exemplary Thioester-Linked Hydrogel as a Sealant inan In Vivo Burn Model

A deep second-degree burn mice model (9 weeks old female Balb/c) wasemployed to assess the wound-healing efficacy of the thioester hydrogelsealant (FIG. 6E). The mice were anesthesized with ketamine (90mg/kg)/xylazine (10 mg/kg) intra-peritoneally and then transferred to awarm environment that maintains a constant body temperature. Burns werecaused through contact with an aluminum bar (r=10 mm) preheated for˜100° C. for ˜15 s, prior to inflicting the burn areas on the skin ofthe mice. The thioester hydrogel was applied to the site of the burnwound and it adhered to the skin for at least several hours. Thereversibility of the thioester hydrogel was also assessed in mice thathad the hydrogel on top of the burn wound (FIG. 6F). Cysteine methylester solution was applied via a syringe on top of the hydrogel and waskept for 30-45 minutes. After this time, the hydrogel was completelydissolved (n=3).

Example 6 Another Example of a Thioester Hydrogel and CharacterizationThereof

In this example, citric acid and NHS-PEG-NHS (e.g., Mw ˜2400 Da) wereused to form a dissolvable hydrogel. The rheological properties wereperformed on a RA 1000 controlled strain rheometer from TA Instrumentequipped with a peltier temperature control. Each sample was allowed toreach the equilibrium at 20° C. for 10 min. 20 mm steel plate diametergeometry was used to measure the rheological properties. All rheologicalmeasurements were performed with a cover and at 20° C. to avoidevaporation. After equilibrium an oscillatory frequency sweep (from 0.1to 10 Hz) was performed at 20° C. This measures the storage modulus G′and the lost modulus G″. All data as shown in FIG. 8C are reported at afrequency of 1 Hz.

In order to form a dissolvable hydrogel using citric acid and PEG-NHS,citric acid was first reacted with a thiol-containing molecule to createa thioester bond in the molecule. For example, as shown in FIG. 8A,N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDCI.HCl)(41.66 mmol) was added to a solution of citric acid (10.4 mmol) andcysteamine hydrochloride (31.2 mmol) in water (40 mL). The reactionmixture was stirred at room temperature overnight. Then, about 30 mL ofNaOH (0.1 M) were added and the product was extracted withdichloromethane (3×100 mL). After evaporation of the solvent the crudeproduct was dissolved in water using HCl 0.1 M until pH 6 thenfreeze-dried to obtain the product A (S,S,S-tris(2-aminoethyl)2-hydroxypropane-1,2,3-tris(carboxylothioate) hydrochloride salt) as awhite powder without further purification. ¹H NMR (CDCl₃): δ=2.4 (s, 4H,CH₂—CO); 3.4 (m, 6H, CH₂—CH₂); 4.0 (m, 6H, CH₂—CH₂) ppm. FAB MS: 391 m/z(M+Na⁺) (theory: 369 m/z (M⁺)).

Then about 50 mg of the product A was dissolved in 1000 μl of phosphatebuffer pH 8 (solution 1) where G′=0 Pa, G″=0 Pa. About 375 mg of PEG-NHSwas dissolved in 1000 μl of phosphate buffer pH 7 (solution 2) whereG′=0 Pa, G″=0 Pa.

As shown in FIG. 8B, a thioester hydrogel was formed within 1 minutewhen solutions 1 and 2 were mixed (Step 1). The thioester hydrogel wasstrong and elastic enough to be handled by hand. The thioester hydrogelhas a shear storage modulus G′ of about 5,200 Pa and a shear lossmodulus G″ of about 1,600 Pa. To dissolve the thioester hydrogel (Step2), the thioester hydrogel was then soaked in a saturated solution ofcysteine (10 mL in water, G′=0 Pa, G″=0 Pa) and all the hydrogel wasresorbed after about 2 hours, as evidenced by the values a G′=0 Pa, G″=0Pa

Example 7 Another Example of a Thioester Hydrogel and CharacterizationThereof

In this example, dendron 1 as shown in FIG. 2 and MAL-thio-PEG-thio-MAL9 (e.g., Mw ˜3400 Da) were used to form a dissolvable hydrogel (FIG.9A). The rheological properties were performed on a RA 1000 controlledstrain rheometer from TA Instrument equipped with a peltier temperaturecontrol. Each sample was allowed to reach the equilibrium at 20° C. for2 min. 8 mm steel plate diameter geometry was used to measure therheological properties. All rheological measurements were performed at20° C. to avoid evaporation. After equilibrium an oscillatory frequencysweep (from 0.1 to 10 Hz) was performed at 20° C. This measures thestorage modulus G′ and the lost modulus G″. The data as shown in FIG. 9Care reported at a frequency of 1 Hz, 50 Pa oscillatory stress and 20° C.

In order to form a dissolvable hydrogel using dendron 1 andMAL-thio-PEG-thio-MAL 9, the second-water soluble macromolecule wassynthesized as detailed in FIG. 9B. For example, to a solution ofSVA-PEG-SVA 3 (3 mmol) in dichloromethane (20 mL), DIPEA (18.7 mmol) andthioglycolic acid (9.37 mmol) were added under nitrogen. The reactionmixture was stirred at room temperature for 16 hours. Then, about 20 mLof citric acid (10 wt %) were added and the product was extracted withdichloromethane (20 mL). The organic phase was then washed with water(25 mL) and brine (25 mL), dried over sodium sulfate, filtered andconcentrated. After evaporation of the solvent, the crude product wastriturated in diethyl ether and after filtration, a white powder 6 (98%)was obtained and used in the next step without further purification. ¹HNMR (500 MHz, CDCl₃): δ=3.77-3.47 (m, ca. 300H), 3.45 (t, J=6.5 Hz, 4H),2.63 (t, J=7.4 Hz, 4H), 1.78-1.72 (m, 4H), 1.63-1.57 (m, 4H) ppm; ¹³CNMR (100 MHz, CDCl₃) δ=197.2, 169.8, 70.4, 70.0, 43.1, 30.9, 28.6, 22.1ppm; MALDI-TOF (pos) (M⁺) 3606; IR (neat) 3485, 2879, 2697, 1714, 1649,1466, 1344, 1110, 949, 842 cm⁻¹.

Compound 6 (3 mmol) was then dissolved in DMF (60 mL) under nitrogen.DIPEA (12 mmol) and PyBOP (7.5 mmol) were added to the solution followedby compound 8 (7.5 mmol). The reaction mixture was stirred at roomtemperature for 16 hours. The reaction mixture was added dropwise tocold diethyl ether and a precipitate is formed. The solid was filtered,washed several times with diethyl ether then dissolved indichloromethane (50 mL). Then, about 50 mL of a saturated solution ofammonium chloride were added and the product was extracted withdichloromethane (50 mL). The organic phase was washed with water, brine,dried over sodium sulfate, filtered and concentrated. After evaporationof the solvent, the crude product was triturated in diethyl ether,filtered and dried. The white powder was then dissolved in water andfiltered. The filtrate was lyophilized to obtain a white powder 9 (90%).¹H NMR (500 MHz, D₂O): δ=6.84 (s, 4H), 3.84-3.6 (m, ca. 304H), 3.55 (m,41-1), 3.42 (m, 4H), 2.71 (m, 4H), 1.72-1.67 (m, 4H), 1.64-1.59 (m, 4H)ppm; ¹³C NMR (100 MHz, CDCl₃) δ=198.8, 170.6, 168.4, 134.1, 70.55, 70.5,70.3, 70.1, 43.18, 38.6, 37.0, 32.3, 28.6, 21.9 ppm; MALDI-TOF (pos)(M⁺) 3852; IR (neat) 3345, 2882, 1710, 1536, 1466, 1343, 1105, 963, 842cm⁻¹.

Synthesis of Compound 8.

To a solution of N-tert-Butoxycarbonyl-1,2-diaminoethane (31.6 mmol) andtriethylamine (47.4 mmol) in diethyl ether (60 mL), was added dropwiseand at 0° C. a solution of maleic anhydride (31.6 mmol) in diethyl ether(60 mL). The reaction mixture was stirred for 4 hours during which thereaction was allowed to reach room temperature. After concentrating thesolution, the residue was dissolved in acetone (150 mL). Triethylamine(47.4 mmol) was added and the mixture heated to reflux. Acetic anhydride(47.8 mmol) was added and the solution heated to reflux for 20 hours.The solvent was then evaporated under vacuum and the crude purified bysilica gel chromatography (cyclohexane/ethyl acetate 1/1). After thecolumn, the product was crystallized in EtOAc/hexane to yield a whitesolid 7 (58%). The NMR spectra are similar to those reported in theliterature (Richter, M. et al. Chem. Eur. J. 2012, 18, 16708-16715).

Compound 7 (17 mmol) was dissolved in dichloromethane (30 mL) and TFA(25 mL) was added at 0° C. The reaction mixture was stirred at roomtemperature for 1 hour then concentrated under vacuum. The crude wastriturated in cold diethyl ether and filtered to yield quantitativelycompound 8 as a white solid. ¹H NMR (500 MHz, DMSO_(d)): δ=8.02 (m, 3H),7.04 (s, 2H), 3.66 (t, J=5.8 Hz, 2H), 2.99 (t, J=5.8 Hz, 2H) ppm.

To form the dissolvable hydrogel, 100 μL solution of dendron 1 (16 mg)in borate buffer pH 9 was mixed to 100 μL solution ofMAL-thio-PEG-thio-MAL 9 (44 mg) in PBS buffer pH 6.5. The hydrogel (30wt %) was formed instantly (1 second).

The efficacy of the dissolvable hemostatic hydrogel was assessed in anin vivo hepatic and aortic injury rat model as shown in FIGS. 9D-9E.Female Sprague Dawley rats were anesthesized with 5% isoflurane in aninduction chamber, then maintained with 2% isoflurane through a nosecone, during the experiments. All animals were anticoagulated withheparin 5 minutes prior to the start of the operation. For hepaticinjury model, the capsule of the median lobe was scored in three spots(lateral, medial, and in the midline), 1 cm from the hepatic border,with a handheld cautery. The portion of the median lobe distal to themarks was sharply excised with scissors. The wound was left to bleed for20 seconds, after which the hydrogel was applied on the wound surface.In the control group, no treatment was administered. After 20 minutes,the blood loss was collected with pre-weighted gauzes and quantified(FIG. 9D, left panel). Similarly, for aortic injury model, a 25-gaugeneedle puncture was made on the abdominal aorta causing severe arterialbleeding. The hydrogel was immediately applied on the wound surface,whereas in the control group no treatment was administered. After 20minutes, the blood loss was quantified and compared to the control (FIG.9E, left panel). The application of the thioester hydrogel on the woundsurface reduced the post-injury blood loss by 35% in severe hepatichemorrhage and by 20% in aortic hemorrhage when compared to untreatedcontrols (p=0.02 and p=0.03, respectively).

The reversibility of the thioester hydrogel was also assessed in the invivo hepatic and aortic injury model. After applying the hydrogel on theincisions, a solution of cysteine methyl ester (e.g., 0.3M) was addedand the hydrogel was completely dissolved (FIGS. 9D-9E, right panel).

Example 8 Another Example of a Thioester Hydrogel and CharacterizationThereof

In this example, dendron 2 and NHS-thio-PEG-thio-NHS 10 (e.g., Mw ˜3400Da) were used to form a dissolvable hydrogel as shown in FIG. 10A. Inthis example, the thio-ester linkage is present within the NHS-PEG-NHScrosslinker. The second-water soluble macromolecule 10 was synthesizedas detailed in FIG. 10B. For example, to a solution of macromer 6 (0.26mmol) in dichloromethane (3 mL), N-hydroxysuccinimide (0.57 mmol) andN,N′-dicyclohexyl carbodiimide (0.57 mmol) were added under nitrogen.The reaction mixture was stirred at room temperature for 16 hours, andthe urea was then removed by filtration. The solvent was evaporatedunder vacuum and the crude triturated in diethyl ether. Afterfiltration, a white solid 10 (60%) was formed. ¹H NMR (500 MHz, CDCl₃):δ=3.61 (m, ca. 300H), 2.81 (s, 8H), 2.66 (m, 4H), 1.77-1.73 (m, 4H),1.62-1.58 (m, 4H) ppm.

In order to form the dissolvable hydrogel, 123 μl solution of dendron 2(16 mg) in borate buffer pH 9 was mixed with 67 μl solution ofNHS-thio-PEG-thio-NHS 10 (42 mg) in PBS buffer pH 6.5. The hydrogel (30wt %) was formed in 10-20 seconds. Application of a solution of cysteinemethyl ester (e.g., about 0.3 M) resulted in the hydrogel beingdissolved.

REFERENCES

-   [1] Bracher, P. J., Snyder, P. W., Bohall, B. R., Whitesides, G. W.    Orig Life Evol Biosph 2011, 41, 399-412-   [2] (a) Yasuyuki, U., Beierle, J. M., Leman, L. J., Orgel, L. E.,    Ghadiri, M. R. Science 2009, 325, 73-77; (b) Yasuyuki, U., Al-Sayah,    M., Montenegro, J., Beierle, J. M., Leman, L. J., Ghadiri, M. R.    Org. Biomol. Chem. 2009, 7, 2878-2884-   [3] (a) Ruan, L., Zhang, H., Luo, H., Liu, J., Tang, F., Shi, Y.-K.,    Zhao, X. PNAS 2009, 106, 5105-5110; (b) Aboushwareb, T., Eberli, D.,    Ward, C., Broda, C., Holcomb, J., Atala, A., Dyke, M. V., J. Biomed.    Mater. Res. Part B: Appl. Biomater. 2009, 90B, 45-54; (c) Hattori,    H., Amano, Y., Nogami, Y., Takase, B., Ishihara, M. Annals of    Biomedical Engineering, 2010, 38, 3724-3732; (d) Luo, Z., Wang, S.,    Zhang, S. Biomaterials, 2011, 32, 2013-2020.-   [4] Alam, H. B., Burris, D., DaCorta, J. A., Rhee, P. Military    Medicine 2005, 170, 63-69-   [5] (a) Hu, B.-H., Su, J., Messersmith, P. B. Biomacromolecules    2009, 10, 2194-2200; (b) Anumolu, S. S., Menjoge, A. R., Deshmukh,    M., Gerecke, D., Stein, S., Laskin, J., Sinko, P. J. Biomaterials    2011, 32, 1204-1217-   [6] (a) Wathier, M., Jung, P. J., Carnahan, M. A., Kim, T.,    Grinstaff, M. W. JACS 2004, 126, 12744-12745; (b) Oelker, A. M.,    Berlin, J. A., Wathier, M., Grinstaff, M. W. Biomacromolecules 2011,    12, 1658-1665-   [7] Wathier, M., Johnson, M. S., Carnahan, M. A., Baer, C.,    McCuen, B. W., Kim, T., Grainstaff, M. W. ChemMedChem 2006, 1,    821-825-   [8] Ghobril, C., Charoen, K., Rodriguez, E. K., Nazarian, A.,    Grinstaff, M. W. Angew. Chem. Int. Ed. 2013, 52, 14070-14074

All patents and other publications identified in the specification andexamples are expressly incorporated herein by reference for allpurposes. These publications are provided solely for their disclosureprior to the filing date of the present application. Nothing in thisregard should be construed as an admission that the inventors are notentitled to antedate such disclosure by virtue of prior invention or forany other reason. All statements as to the date or representation as tothe contents of these documents is based on the information available tothe applicants and does not constitute any admission as to thecorrectness of the dates or contents of these documents.

What is claimed is:
 1. A method comprising: (a) contacting a wound witha hydrogel composition comprising a dissolvable hydrogel layer, whereinthe dissolvable hydrogel layer comprises linear, branched, and/ordendritic crosslinkable polymers held together by covalent bonds formedbetween the first crosslinkable polymer and the second crosslinkablepolymer, wherein the dissolvable hydrogel layer comprises thioesterlinkages; and (b) allowing the dissolvable hydrogel layer to adhere totissue surrounding the wound.
 2. The method of claim 1, furthercomprising dissolving the dissolvable hydrogel layer by adding athiolate compound to result in a thiol-thioester exchange, therebyreleasing the hydrogel composition from the wound.
 3. A methodcomprising: (a) contacting a wound with a hydrogel compositioncomprising a dissolvable hydrogel layer, wherein the dissolvablehydrogel layer comprises linear, branched, and/or dendriticcrosslinkable polymers held together by thioester linkages formedbetween the first crosslinkable polymer and the second crosslinkablepolymer; (b) allowing the dissolvable hydrogel layer to adhere to tissuesurrounding the wound; and (c) dissolving the dissolvable hydrogel layerby adding a thiolate compound to result in a thiol-thioester exchange,thereby releasing the hydrogel composition from the wound.
 4. The methodof any of claims 1-3, wherein the dissolvable hydrogel layer is derivedfrom a first water-soluble linear, branched, and/or dendriticcrosslinkable polymer comprising at least two thiol moieties and asecond water-soluble linear, branched, and/or dendritic crosslinkablepolymer comprising at least two crosslinking moieties that are capableof reacting with said at least two thiol moieties of the firstcrosslinkable polymer to form the thioester linkages between the firstand second crosslinkable polymers.
 5. The method of claim 1 or 2,wherein the dissolvable hydrogel layer is derived from a firstwater-soluble linear, branched, and/or dendritic crosslinkable polymercomprising at least two thioester linkages and a second water-solublelinear, branched, and/or dendritic crosslinkable polymer comprising atleast two crosslinking moieties that are capable of forming a linkagewith the first water-soluble linear, branched, and/or dendritic polymer.6. The method of claim 1 or 2, wherein the dissolvable hydrogel layer isderived from a first water-soluble linear, branched and/or dendriticcrosslinkable polymer comprising at least two nucleophilic moieties thatare capable of forming a linkage with at least two crosslinking moietiesof the second-water soluble linear, branched and/or dendritic polymer;wherein at least one of the first and second water-soluble linear,branched and/or dendritic crosslinkable polymers comprises at least twothioester linkages.
 7. The method of any of claims 1-6, wherein thelinear crosslinkable polymer comprises polyesters, polyethers,polyether-esters, polyglycerols, polyamino acids, polyester-amines,polyurethanes, polycarbonates, polyamino alcohols, thiols, amines,N-hydroxysuccinimide (NHS) moieties, maleimide (MAL) moieties, or anycombinations thereof.
 8. The method of any of claims 1-7, wherein thebranched crosslinkable polymer comprises polyesters, polyethers,polyether-esters, polyglycerols, polyamino acids, polyester-amines,polyurethanes, polycarbonates, polyamino alcohols, thiols, amines,N-hydroxysuccinimide (NHS) moieties, Maleimide (MAL) moieties, or anycombinations thereof.
 9. The method of any of claims 1-8, wherein thedendritic crosslinkable polymer comprises polyesters, polyethers,polyether-esters, polyamino acids, polyester-amines, polyurethanes,polycarbonates, polyamino alcohols, thiols, amines, N-hydroxysuccinimide(NHS) moieties, Maleimide (MAL) moieties, or any combinations thereof.10. The method of any of claims 1-9, wherein the first crosslinkablepolymer has a chemical structure selected from the group consisting ofstructure (i)-structure (xii) shown as follows:

and any combinations thereof; and wherein: Q is independently selectedfrom the group consisting of O, S, Se, NH, CH₂ and any combinationthereof; R is selected from the group consisting of a hydrogen, straightor branched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and m, n, and x are eachindependently selected from an integer of 0-1000.
 11. The method of anyof claims 4-10, wherein said at least two crosslinking moieties compriseat least one N-hydroxysuccinimide (NHS) or maleimide (MAL) moeity. 12.The method of any of claims 4-10, wherein said at least two crosslinkingmoieties comprise at least two N-hydroxysuccinimide (NHS) or maleimide(MAL) moeities.
 13. The method of any of claims 1-12, wherein the secondcross-linkable polymer has a chemical structure selected from the groupconsisting of structure (xiii)-structure (xl) shown as follows:

and any combination thereof; and wherein Q is independently selectedfrom the group consisting of O, S, Se, NH, CH₂ and any combinationthereof; R is selected from the group consisting of a hydrogen, straightor branched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and m, n, x, y and z areeach independently selected from an integer of 0-1000.
 14. The method ofany of claims 10-13, wherein R is selected from the group consisting ofpoly(ethylene glycol), poly(ethylene oxide), poly(hydroxyacid), acarbohydrate, a protein, a polypeptide, an amino acid, a nucleic acid, anucleotide, a polynucleotide, a DNA segment, a RNA segment, a lipid, apolysaccharide, an antibody, a pharmaceutical agent, an epitope for abiological receptor, and any combinations thereof.
 15. The method of anyof claims 1-14, wherein the thiolate compound is selected from the groupconsisting of linear, branched and/or dendritic multi-thiolmacromolecule, poly(ethylene glycol) thiol, thiol containing glycerol,thiol containing peptide, cysteine, cystine, alkyl ester of cysteine,alkyl ester of cystine, MeSCH₂SH, (R)/(S)-3-methyl-3-sulfanylhexan-1-ol,Ethanethiol, 1-Propanethiol, 2-Propanethiol, Butanethiol, tert-Butylmercaptan, Pentanethiols, Thiophenol, Dimercaptosuccinic acid,Thioacetic acid, 5-mercapto-4H-[1,2,4]triazol-3-ol, 2-mercaptoacetamide,2-Mercaptoethanol, 1,2-Ethanedithiol, Ammonium thioglycolate,Cysteamine, Methyl thioglycolate, Thiolactic acid,1-Mercapto-2-propanol, 2-methoxyethanethiol, 3-Mercapto-1-propanol,2,3-Dimercapto-1-propanol, 1-Thioglycerol, Mercaptosuccinic acid,4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol, N-Carbamoyl-L-cysteine,2-Methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid,N-Acetylcysteamine, 3-Methyl-1-butanethiol, 1,5-Pentanedithiol,4-Chlorothiophenol, 4-Aminothiophenol, Benzyl mercaptan,2-Furanmethanethiol, 3-Mercaptohexanol, Furfuryl thiol, derivativesthereof, a disulfide complex of one or more thereof, and anycombinations thereof.
 16. The method of any of claims 1-15, wherein thedissolvable hydrogel layer is at least partially flexible.
 17. Themethod of any of claims 1-16, wherein the dissolvable hydrogel layer isat least partially adhesive.
 18. The method of any of claims 1-17,wherein the dissolvable hydrogel layer is capable of withstanding apressure of at least about 2 mmHg.
 19. The method of any of claims 1-18,wherein the dissolvable hydrogel layer is transparent.
 20. The method ofany of claims 1-19, wherein the dissolvable hydrogel layer ishydrophilic.
 21. The method of any of claims 1-20, wherein thedissolvable hydrogel layer is elastic or viscoelastic.
 22. The method ofany of claims 1-21, wherein the dissolvable hydrogel layer has about 5wt % to about 70 wt % of the crosslinkable polymers.
 23. The method ofany of claims 1-22, wherein the hydrogel composition further comprises abioactive agent.
 24. The method of claim 23, wherein the bioactive agentis selected from the group consisting of pharmaceutical agents, drugs,cells, gases and gaseous precursors, synthetic organic molecules,proteins, enzymes, growth factors, vitamins, steroid, polyanions,nucleosides, nucleotides, polynucleotides, nanoparticles, diagnosticagents, genetic materials, and any combinations thereof.
 25. The methodof any of claims 1-24, wherein the hydrogel composition is formulated toform a bandage, glue, sealant, dressing, scaffold, coating, or covering.26. The method of any of claims 1-25, wherein the hydrogel compositionis used with vacuum assisted closure.
 27. The method of any of claims1-26, wherein the thiolate compound is formulated as a solution or aspray.
 28. A dissolvable hydrogel composition comprising: an adhesivehydrogel layer comprising a first water-soluble linear, branched, and/ordendritic crosslinkable polymer and a second water-soluble linear,branched, and/or dendritic crosslinkable polymer held together bythioester linkages formed between the first crosslinkable polymer andthe second crosslinkable polymer, wherein the first crosslinkablepolymer comprises at least two thiol moieties and the secondcrosslinkable polymer comprises at least two crosslinking moieties thatare capable of reacting with said at least two thiol moieties of thefirst crosslinkable polymer to form the thioester linkages between thefirst crosslinkable polymer and the second crosslinkable polymer.
 29. Adissolvable hydrogel composition comprising: an adhesive hydrogel layercomprising a first water-soluble linear, branched and/or dendriticcrosslinkable polymer and a second water-soluble linear, branched and/ordendritic crosslinkable polymer held together by covalent bonds formedbetween the first crosslinkable polymer and the second crosslinkablepolymer, wherein the adhesive hydrogel layer comprises thioesterlinkages.
 30. The dissolvable hydrogel composition of claim 29, whereinthe first crosslinkable polymer comprises at least two thiol moietiesand the second crosslinkable polymer comprises at least two crosslinkingmoieties that are capable of reacting with said at least two thiolmoieties of the first crosslinkable polymer to form the thioesterlinkages between the first crosslinkable polymer and the secondcrosslinkable polymer;
 31. The dissolvable hydrogel composition of claim29, wherein the first crosslinkable polymer comprises at least twothioester linkages and the second crosslinkable polymer comprises atleast two crosslinking moieties that are capable of forming a linkagewith the first crosslinkable polymer.
 32. The dissolvable hydrogelcomposition of claim 29, wherein the first crosslinkable polymercomprises at least two nucleophilic moieties that are capable of forminga linkage with at least two crosslinking moieties of the secondcrosslinkable polymer that comprises at least two thioester linkages.33. The dissolvable hydrogel composition of any of claims 28-32, whereinthe linear crosslinkable polymer comprises polyesters, polyethers,polyglycerols, polypeptides, polyether-esters, polyamino acids,polyester-amines, polyurethanes, polycarbonates, polyamino alcohols,thiols, amines, N-hydroxysuccinimide (NHS) moieties, maleimide (MAL)moieties, or any combinations thereof.
 34. The dissolvable hydrogelcomposition of any of claims 28-33, wherein the branched crosslinkablepolymer comprises polyesters, polyethers, polyglycerols, polypeptides,polyether-esters, polyamino acids, polyester-amines, polyurethanes,polycarbonates, polyamino alcohols, thiols, amines, N-hydroxysuccinimide(NHS) moieties, maleimide (MAL) moiety, or any combinations thereof. 35.The dissolvable hydrogel composition of any of claims 28-34, wherein thedendritic crosslinkable polymer comprises polyesters, polyethers,polyglycerols, polypeptides, polyether-esters, polyamino acids,polyester-amines, polyurethanes, polycarbonates, polyamino alcohols,thiols, amines, N-hydroxysuccinimide (NHS) moieties, maleimide (MAL)moieties, or any combinations thereof.
 36. The dissolvable hydrogelcomposition of any of claims 28-35, wherein when both the first andsecond crosslinkable polymers are branched or dendritic crosslinkablepolymers, at least one of the first and the second dendriticcrosslinkable polymers docs not comprise poly(ethylene glycol).
 37. Thedissolvable hydrogel composition of any of claims 28-36, wherein thefirst crosslinkable polymer has a chemical structure selected from thegroup consisting of structure (i) to structure (xii) shown as follows:

and any combinations thereof; and wherein: Q is independently selectedfrom the group consisting of O, S, Se, NH, CH₂, and any combinationthereof; R is selected from the group consisting of a hydrogen, straightor branched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; when at least two R groupsare in the same structure, R can be different from each other and m, n,x, and y are each independently selected from an integer of 0-1000. 38.The dissolvable hydrogel composition of any of claims 28-37, whereinsaid at least two crosslinking moieties comprise at least oneN-hydroxysuccinimide (NHS) moiety or maleimide (MAL) moiety.
 39. Thedissolvable hydrogel composition of any of claims 28-38, wherein said atleast two crosslinking moieties comprise at least twoN-hydroxysuccinimide (NHS) moieties or maleimide (MAL) moieties.
 40. Thedissolvable hydrogel composition of any of claims 28-39, wherein thesecond crosslinkable polymer has a chemical structure selected from thegroup consisting of structure (xiii) to structure (xl) shown follows:

and any combination thereof; and wherein Q is independently selectedfrom the group consisting of O, S, Se, NH, CH₂, and any combinationthereof; R is selected from the group consisting of a hydrogen, straightor branched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; when at least two R groupsare in the same structure, R can be different from each other and m, n,x, y and z are each independently selected from an integer of 0-1000.41. The dissolvable hydrogel composition of any of claims 37-40, whereinR is selected from the group consisting of poly(ethylene glycol),poly(ethylene oxide), poly(hydroxyacid), a carbohydrate, a protein, apolypeptide, an amino acid, a nucleic acid, a nucleotide, apolynucleotide, a DNA segment, a RNA segment, a lipid, a polysaccharide,an antibody, a pharmaceutical agent, an epitope for a biologicalreceptor, and any combinations thereof.
 42. The dissolvable hydrogelcomposition of any of claims 28-41, wherein the first crosslinkablepolymer has a chemical structure as follows:


43. The dissolvable hydrogel composition of any of claims 28-42, whereinthe second crosslinkable polymer is poly(ethylene glycol) disuccinimidylvalerate.
 44. The dissolvable hydrogel composition of any of claims28-43, wherein the adhesive hydrogel layer is at least partiallyflexible.
 45. The dissolvable hydrogel composition of any of claims28-44, wherein the adhesive hydrogel layer is capable of withstanding apressure of at least about 2 mmHg.
 46. The dissolvable hydrogelcomposition of any of claims 28-45, wherein the adhesive hydrogel layeris transparent.
 47. The dissolvable hydrogel composition of any ofclaims 28-46, wherein the adhesive hydrogel layer is hydrophilic. 48.The dissolvable hydrogel composition of any of claims 28-47, wherein theadhesive hydrogel layer is elastic or viscoelastic.
 49. The dissolvablehydrogel composition of any of claims 28-48, wherein the adhesivehydrogel layer has about 5 wt % to about 70 wt % of the crosslinkablepolymers.
 50. The dissolvable hydrogel composition of any of claims28-49, further comprising a bioactive agent.
 51. The dissolvablehydrogel composition of claim 50, wherein the bioactive agent isselected from the group consisting of pharmaceutical agents, drugs,cells, gases and gaseous precursors, synthetic organic molecules,proteins, enzymes, growth factors, vitamins, steroids, polyanions,nucleosides, nucleotides, polynucleotides, nanoparticles, diagnosticagents, genetic materials, and any combinations thereof.
 52. Thedissolvable hydrogel composition of any of claims 28-51, wherein theadhesive layer is hydrolytically stable at pH in a range of about 0 toat least about
 9. 53. The dissolvable hydrogel composition of any ofclaims 28-52, wherein the dissolvable hydrogel composition is formulatedto form a bandage, glue, sealant, dressing, scaffold, coating, orcovering.
 54. The dissolvable hydrogel composition of any of claims28-53, wherein the dissolvable hydrogel composition is adapted for usewith vacuum assisted closure.
 55. A kit comprising: a dissolvablehydrogel composition comprising: an adhesive hydrogel layer comprisinglinear, branched, and/or dendritic crosslinkable polymers held togetherby thioester linkages formed between the linear, branched, and/ordendritic crosslinkable polymers; and a thiolate compound.
 56. A kitcomprising: a dissolvable hydrogel composition comprising: an adhesivehydrogel layer comprising linear, branched and/or dendrite crosslinkablepolymers held together by covalent bonds formed between the firstcrosslinkable polymer and the second crosslinkable polymer, wherein theadhesive hydrogel layer comprises thioester linkages; and a thiolatecompound.
 57. The kit of claim 56, wherein the adhesive hydrogel layeris derived from a first water-soluble linear, branched, and/or dendriticcrosslinkable polymer comprising at least two thiol moieties and asecond water-soluble linear, branched, and/or dendritic crosslinkablecomprising at least two crosslinking moieties that are capable ofreacting with said at least two thiol moieties of the firstcrosslinkable polymer to form the thioester linkages between the firstand the second crosslinkable polymers.
 58. The kit of claim 56, whereinthe adhesive hydrogel layer is derived from a first water-solublelinear, branched, and/or dendritic crosslinkable polymer comprising atleast two thioester linkages and a second water-soluble linear,branched, and/or dendritic crosslinkable polymer comprising at least twocrosslinking moieties that are capable of forming a linkage with thefirst water-soluble linear, branched, and/or dendritic polymer.
 59. Thekit of claim 56, wherein the adhesive hydrogel layer is derived from afirst water-soluble linear, branched and/or dendritic crosslinkablepolymer comprising at least two nucleophilic moieties that are capableof forming a linkage with the second water-soluble linear, branchedand/or dendritic polymer, wherein at least one of the first and secondwater-soluble linear, branched and/or dendritic crosslinkable polymerscomprises at least two thioester linkages.
 60. The kit of any of claims55-59, wherein the adhesive hydrogel layer is hydrolytically stable atpH in a range of about 0 to at least about
 9. 61. The kit of any ofclaims 55-60, wherein the adhesive hydrogel layer has a larger molecularweight than the crosslinkable polymers.
 62. The kit of any of claims55-61, wherein the adhesive hydrogel layer has a molecular weight of atleast about 100 kDa.
 63. The kit of any of claims 55-62, wherein thedissolvable hydrogel composition is formulated to form a bandage,sealant, coating or covering.
 64. The kit of any of claims 55-63,further comprising at least one component for performing vacuum assistedclosure.
 65. The kit of any of claims 55-64, wherein the dissolvablehydrogel composition further comprises a bioactive agent.
 66. A kitcomprising: a first water-soluble linear, branched, and/or dendriticcrosslinkable polymer comprising at least two thiol moieties, whereinthe first crosslinkable polymer is at least about 200 Da; a secondwater-soluble linear, branched, and/or dendritic crosslinkable polymerthat can react with the first crosslinkable polymer to form adissolvable and adhesive hydrogel, wherein the second crosslinkablepolymer comprises at least two crosslinking moieties that are capable ofreacting with the thiol moieties of the first crosslinkable polymer toform thioester linkages between the first and the second crosslinkablepolymers; and wherein the second crosslinkable polymer is at least about200 Da; and a thiolate compound.
 67. A kit comprising: a firstwater-soluble linear, branched, and/or dendritic crosslinkable polymercomprising at least two thioester linkages, wherein the firstcrosslinkable polymer is at least about 200 Da; a second water-solublelinear, branched, and/or dendritic crosslinkable polymer that can reactwith the first crosslinkable polymer to form a dissolvable and adhesivehydrogel, wherein the second crosslinkable polymer comprises at leasttwo crosslinking moieties that are capable of forming a linkage with thefirst crosslinkable polymer; and wherein the second crosslinkablepolymer is at least about 200 Da; and a thiolate compound.
 68. A kitcomprising: a first water-soluble linear, branched and/or dendriticcrosslinkable polymer that can react with the second crosslinkablepolymer to form a dissolvable and adhesive thioester hydrogel, whereinthe first crosslinkable polymer comprises at least two nucleophilicmoieties that are capable of forming a linkage with the secondcrosslinkable polymer; and wherein the first crosslinkable polymer is atleast about 200 Da; a second water-soluble linear, branched and/ordendritic crosslinkable polymer comprising at least two thioesterlinkages, wherein the second crosslinkable polymer is at least about 200Da; and a thiolate compound.
 69. The kit of any of claims 55-68, whereinthe first crosslinkable polymer, the second crosslinkable polymer, andthe thiolate compound are each independently formulated in a formselected from the group consisting of a spray, a foam, a solution, apowder, and any combinations thereof.
 70. The kit of any of claims55-69, further comprising a bioactive agent.
 71. The kit of claim 70,wherein the bioactive agent is selected from the group consisting ofpharmaceutical agents, drugs, cells, gases and gaseous precursors,synthetic organic molecules, proteins, enzymes, growth factors,vitamins, steroids, polyanions, nucleosides, nucleotides,polynucleotides, nanoparticles, diagnostic agents, genetic materials,and any combinations thereof.
 72. The kit of any of claims 55-71,wherein the thiolate compound is provided in an amount such that thestoichiometric ratio of the number of thiols in the thiolate compound tothe number of thioester linkages in the dissolvable hydrogel is greaterthan 1:1.
 73. The kit of any of claims 55-72, wherein the firstcrosslinkable polymer has a chemical structure selected from the groupconsisting of structure (i) to structure (xii) shown as follows:

and any combinations thereof; and wherein: Q is independently selectedfrom the group consisting of O, S, Se, NH, CH₂ and any combinationthereof; R is selected from the group consisting of a hydrogen, straightor branched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and m, n, x, and y are eachindependently selected from an integer of 0-1000.
 74. The kit of any ofclaims 55-73, wherein said at least two crosslinking moieties of thesecond crosslinkable polymer comprises at least one N-hydroxysuccinimide(NHS) moiety or maleimide (MAL) moiety.
 75. The kit of any of claims55-74, wherein said at least two crosslinking moieties of the secondcrosslinkable polymer comprises at least two N-hydroxysuccinimide (NHS)moieties or maleimide (MAL) moieties.
 76. The kit of any of claims55-75, wherein the second crosslinkable polymer has a chemical structureselected from the group consisting of structure (xiii) to structure (xl)shown as follows:

and any combination thereof; and wherein Q is independently selectedfrom the group consisting of O, S, Se, NH, CH₂ and any combinationthereof; R is selected from the group consisting of a hydrogen, straightor branched alkyl, cycloalkyl, aryl, olefin or alkene, alkyne, silyl,alkylsilyl, arylsilyl, alkylaryl or arylalkyl chain of 1-50 carbons,fluorocarbon, and any combinations thereof, wherein each alkyl,cycloalkyl, aryl, olefin, alkyne, alkyne, silyl, alkylsilyl, arylsilyl,alkylaryl, fluorocarbon, or arylalkyl chain is optionally substitutedinternally or terminally by one or more hydroxyl, hydroxyether,carboxyl, carboxyester, carboxyamide, amino, mono- or di-substitutedamino, thiol, thioester, sulfate, phosphate, phosphonate, halogensubstituents; and any combinations thereof; and m, n, x, y, and z areeach independently selected from an integer of 0-1000.
 77. The kit ofany of claims 73-76, wherein R is selected from the group consisting ofpoly(ethylene glycol), poly(ethylene oxide), poly(hydroxyacid), acarbohydrate, a protein, a polypeptide, an amino acid, a nucleic acid, anucleotide, a polynucleotide, a DNA segment, a RNA segment, a lipid, apolysaccharide, an antibody, a pharmaceutical agent, an epitope for abiological receptor, and any combinations thereof.
 78. The kit of any ofclaims 55-77, wherein the first crosslinkable polymer has a chemicalstructure as follows:


79. The kit of any of claims 55-78, wherein the first crosslinkablepolymer has a chemical structure as follows:


80. The kit of any of claims 55-79, wherein the second crosslinkablepolymer is poly(ethylene glycol) disuccinimidyl valerate.
 81. The kit ofany of claims 55-80, wherein the thiolate compound is selected from thegroup consisting of linear, branched and/or dendritic multi-thiolmacromolecules, poly(ethylene glycol) thiol, thiol-containing glycerol,thiol-containing peptides, cysteine, cystine, alkyl ester of cysteine,alkyl ester of cystine, MeSCH₂SH, (R)/(S)-3-methyl-3-sulfanylhexan-1-ol,Ethanethiol, 1-Propanethiol, 2-Propanethiol, Butanethiol, tert-Butylmercaptan, Pentanethiols, Thiophenol, Dimercaptosuccinic acid,Thioacetic acid, 5-mercapto-4H-[1,2,4]triazol-3-ol, 2-mercaptoacetamide,2-Mercaptoethanol, 1,2-Ethanedithiol, Ammonium thioglycolate,Cysteamine, Methyl thioglycolate, Thiolactic acid,1-Mercapto-2-propanol, 2-methoxyethanethiol, 3-Mercapto-1-propanol,2,3-Dimercapto-1-propanol, 1-Thioglycerol, Mercaptosuccinic acid,4-ethyl-5-mercapto-4H-1,2,4-triazol-3-ol, N-Carbamoyl-L-cysteine,2-Methyl-3-sulfanylpropanoic acid, 4-mercaptobutyric acid,N-Acetylcysteamine, 3-Methyl-1-butanethiol, 1,5-Pentanedithiol,4-Chlorothiophenol, 4-Aminothiophenol, Benzyl mercaptan,2-Furanmethanethiol, 3-Mercaptohexanol, Furfuryl thiol, derivativesthereof, a disulfide complex of one or more thereof.
 82. The kit of anyof claims 55-81, wherein the adhesive hydrogel layer is at leastpartially flexible.
 83. The kit of any of claims 55-82, wherein theadhesive hydrogel layer is capable of withstanding a pressure of atleast about 2 mmHg.
 84. The kit of any of claims 55-83, wherein theadhesive hydrogel layer is transparent.
 85. The kit of any of claims55-84, wherein the adhesive hydrogel layer is hydrophilic.
 86. The kitof any of claims 55-85, wherein the adhesive hydrogel layer is elasticor viscoelastic.
 87. The kit of any of claims 55-86, wherein theadhesive hydrogel layer has about 5 wt % to about 70 wt % of thecrosslinkable polymers.
 88. A kit of any of claims 55-87 for treatmentof a wound in a tissue of a subject.
 89. The kit of claim 88, whereinthe tissue is selected from the group consisting of skin, heart, bloodvessel, liver, urinary tract, lung, gastrointestinal tract, stomach,joint, bone, brain, ear, alveolar bone, lymphatic tissue, buccal tissue,and any combinations thereof.